M91/FastHall Station references in research literature

Transparent conductive oxide (TCO) films are widely used as electrodes in photovoltaic devices, such as perovskite solar cells and heterojunction solar cells. However, in the conventional physical vapor deposition process, ion bombardment may damage the underlayer coatings, and high deposition temperature also adversely affects perovskite and amorphous silicon layers during TCO deposition. Herein, reactive plasma deposition was effectively utilized for cerium-doped indium oxide (ICO) film as an ultra-transparent electrode. The effects of plasma gun current and the oxygen ratio on the optical and electrical properties, and also on the structure of the ICO films, were investigated. With an industry-scale reactive plasma deposition tool, an outcome of 140 nm ICO film can be achieved within 50 s, which represents a good throughput with an average growth rate of 2.8 nm/s. When the working current was 165 A and the oxygen ratio was 12%, the average transmittance of ICO films reached the highest value (93.09%) in the wavelength range of 400 to 1200 nm. The average transmittance in the visible wavelength range was 94.23%. The peak transmittance was up to 99.67% at 515 nm, and the corresponding resistivity was 4.68 × 10⁻⁴ Ω cm.

AB₂Sb₂-type Zintl phases, especially Mg₃Sb₂, have garnered widespread attention by virtue of their nontoxic constituent elements and outstanding thermoelectric performance in n-type materials. However, the p-type counterpart of AB₂Sb₂ still struggles with a low figure of merit zT, primarily because of the limited valence band degeneracy, large band effective mass, and relatively high thermal conductivity. Here, we simultaneously optimize the electrical and thermal transports of p-type AB₂Sb₂-based materials by shaping the band edge and distorting the crystal lattice. By alloying Zn at the Mg2 site and Ca at the Mg1 site, we successfully decorate the crystal lattice of Mg₃Sb₂ in real space and thereby modify the band structure in reciprocal space. Zn alloying promotes band degeneracy while Ca alloying reduces the single band effective mass, which largely promotes the transport of charge carriers. Moreover, the distorted crystal lattice effectively blocks the heat-carry phonons to reduce the lattice thermal conductivity κ_L. A high zT of 0.81 is finally realized at 750 K in our Zn/Ca co-alloyed samples, which is three times larger than that of the Mg₃Sb₂ matrix. Our work opens new possibilities for the synthetic optimization of both electrical and thermal transports in Zintl phase and other thermoelectric systems.

High-quality Ta-doped ZnSnO₃ single crystal thin films were grown on LiTaO₃ substrates by pulsed laser deposition (PLD) method, and the effects of Ta doping on the lattice structure, surface morphology, electronic structure and photodetector performance of ZnSnO₃ thin films are studied in detail. When the Ta doping content is 1%, the [0001]-oriented ZnSnO₃ thin film present the highest quality, which the optical band gap (3.75 eV), the smoothest surface roughness (0.83 nm), and the biggest carrier concentration (4.03 × 10¹⁹ cm⁻³). For the solar-blind photodetectors (PDs), based on these excellent characteristics, the 1% Ta-doped ZnSnO₃ PD exhibits large light-to-dark current ratio (>10³), responsivity (21.37 A/W), detectivity ((3.63±0.71) × 10¹¹ Jones) and external quantum efficiency (∼1.04 × 10⁴%) under 254 nm UV light at an applied bias of 5 V. This study suggests that Ta doping can effectively improve the optoelectronic performance of ZnSnO₃ PDs, laying the foundation for their application.

This study reports the successful growth of aligned Cu-doped β-Ga₂O₃ nanoarrays using the chemical vapor deposition (CVD) method. A MgO substrate was employed for epitaxial growth of Ga₂O₃ due to the lower lattice mismatch compared to sapphire and silicon. The morphology, growth mechanism, and optical and photoelectrochemical properties of Cu-doped β-Ga₂O₃ nanoarrays were thoroughly characterized. The experimental results indicate that doped Cu exists in the form of monovalent cuprous ions Cu⁺. Additionally, the β-Ga₂O₃ nanoarrays will exhibit p-type semiconductor properties after Cu doping at certain conditions. Therefore, this material has great potential for applications, particularly in the fields of photoelectrocatalysis and photoluminescence. These research findings provide an important reference for expanding the new application areas of Ga₂O₃.

Thin-film tandem photovoltaic (PV) technology has emerged as a promising avenue to enhance power conversion efficiency beyond the radiative efficiency limit of single-junction devices. Combining a tunable wide-bandgap perovskite cell with a commercially established narrow-bandgap cadmium selenium telluride (CdSeTe) cell in a comparatively easy-to-fabricate four-terminal (4-T) arrangement is a great step in that direction. Herein, the impact of the transparent back contact and the perovskite absorber bandgap on the performance of 4-T perovskite–CdSeTe tandem solar cells is investigated. 4-T perovskite–CdSeTe tandem device architecture with ≈25% efficiency is demonstrated and a feasible pathway is shown to improve the tandem efficiency to more than 30%. The results show that the integration of CdSeTe with perovskite in 4-T tandem PV configurations represents a significant advancement toward achieving higher efficiency and low-cost tandem PVs.

Ag/Bi₂Sn₂O₇ materials have high electrical conductivity but mechanical properties similar to those of Ag/SnO₂ owing to their poor Ag/Bi₂Sn₂O₇ interfacial wettability. In this study, Ni-doped Ag/Bi₂Sn₂O₇ was prepared by high-energy ball milling, powder metallurgy, and extrusion. The microstructures and physical, mechanical, and electrical properties of Ag/Bi₂Sn₂O₇ (Ni-doped) materials with different Ni molar fractions were investigated by XRD, SEM, XPS, Hall-effect tests, metal resistivity measurements, tensile tests, and electrical life tests. The formation of a crystalline Ni-containing solid solution is also confirmed. With an increase in the Ni-doping molar fraction from 0 to 8.3%, the resistivity of the Ni-doped Bi₂Sn₂O₇ powder increased, the Ag/Bi₂Sn₂O₇ interfacial wetting angle decreased from 104.6°, to 83.1°, the hardness and density of the Ag/Bi₂Sn₂O₇ (Ni-doped) material first increased and then decreased, while the resistivity exhibited an opposite tendency. The Ag/Bi₂Sn₂O₇–5.2Ni (sheets) exhibited the lowest resistivity of 2.00 µΩ·cm, the highest hardness of 687 MPa, and the highest density of 9.99 g/cm³; its electrical life was 1.6 and 1.8 times that of Ag/Bi₂Sn₂O₇ and Ag/SnO₂, respectively. Thus, an appropriate amount of Ni-doping can improve the interfacial wettability, physical properties, and electrical properties of Ag/Bi₂Sn₂O₇ electrical contact materials.

As gallium oxide-based heterojunction devices gain prominence, low-resistance contacts to aluminum gallium oxide material are of increasing importance for high performance and access to modulation doped layers. Here, the activation of ion-implanted silicon donors is investigated as a function of donor density from 5 × 10¹⁸ cm⁻³ to 1 × 10²⁰ cm⁻³, activation anneal duration from 6 s to 600 s, and activation temperature from 900°C to 1140°C. Importantly, ohmic behavior was achievable across a reasonably wide process window at moderate to high doping concentrations. Specific contact resistance of 1 × 10⁻³ Ω cm² and sheet resistance of 2.8 kΩ/□ were achieved for a 60 nm-deep 1 × 10²⁰ cm⁻³ box implant after activation at 1000°C for 6 s with standard Ti/Au contacts. Under these conditions, an activation efficiency of 7% was observed with Hall mobility of ~32 cm²/Vs. Furthermore, we demonstrate a Schottky diode formed of implanted material with a rectification ratio > 10⁶ and further confirm the Hall carrier density results using capacitance–voltage profiling analysis. Finally, we show the significant impact of anneal duration and the potential for deleterious over-annealing which reduces the active carrier density, mobility, and resultant material conductivity.

The doping levels of conjugated polymers significantly influence their conductivity, energetics, and optical properties. Recently, a highly conductive n-doped polymer called poly (3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dione) (poly(benzodifurandione), n-PBDF) is discovered, opening new possibilities for n-type conducting polymers in printed electronics and other fields. Controlling the doping level of n-PBDF is of great interest due to its wide range of potential applications. Here controlled dedoping and redoping of n-PBDF is reported and a mechanistic understating of such a process is provided. Dedoping occurs through electron transfer and proton capture, wherein the ionic dopants, tris(4-bromophenyl)ammoniumyl hexachloroantimonate (Magic Blue), exhibit efficient proton capture ability and stronger interaction with n-PBDF, resulting in high dedoping efficiency. Moreover, chemically dedoped PBDF can be redoped using various proton-coupled electron transfer agents. By manipulating the doping levels of n-PBDF thin films, ranging from highly doped to dedoped states, the system demonstrates controllable conductivity in five orders of magnitude, adjustable optical properties, and energetics. As a result, these characteristics demonstrate the potential applications of n-PBDF in organic electrochemical transistors and thermoelectrics.

The application of machine learning in materials science has yielded several benefits, including the prediction of physical properties and the improvement of experimental efficiency. However, with complex models, such as convolutional neural networks (CNN), learning has become a black box, from which no universal physical knowledge can be obtained. In this study, a highly accurate prediction of the electrical properties of polycrystalline semiconductor thin films is achieved by learning multichannel CNN models from electron backscattering diffraction (EBSD) data, that is band contrasts, grain boundaries, and inverse pole figures. In addition, it examines how the CNN model learned the correlation between the crystallinity, grain boundaries, crystallographic orientation, and carrier mobility by polarizing certain EBSD data and checking the predicted changes in carrier mobility. Physical parameters affecting carrier mobility can be extracted, which is challenging via human image recognition. The methods proposed in this study will not only enable the prediction of electrical properties from EBSD data for all materials but also will contribute to the discovery of complex physical phenomena beyond the limits of human analysis.

Beta gallium oxide (⁠𝛽-Ga₂O₃)-based semiconductor heterojunctions have recently demonstrated improved performance at high voltages and elevated temperatures and are, thus, promising for applications in power electronic devices and harsh environment sensors. However, the long-term reliability of these ultra-wideband gap (UWBG) semiconductor devices remains barely addressed and may be strongly influenced by chemical reactions at the p–n heterojunction interface. Here, we experimentally demonstrate operation and evaluate the reliability of Cr₂O₃:Mg/β-Ga₂O₃ p–n heterojunction diodes during extended operation at 600 °C, as well as after 30 repeated cycles between 25 and 550 °C. The calculated pO₂-temperature phase stability diagram of the Ga-Cr-O material system predicts that Ga₂O₃ and Cr₂O₃ should remain thermodynamically stable in contact with each other over a wide range of oxygen pressures and operating temperatures. The fabricated Cr₂O₃:Mg/ 𝛽-Ga₂O₃ p–n heterojunction diodes show room-temperature on/off ratios >10⁴ at ±5 V and a breakdown voltage (V_Br) of −390 V. The leakage current increases with increasing temperature up to 600 °C, which is attributed to Poole–Frenkel emission with a trap barrier height of 0.19 eV. Over the course of a 140-h thermal soak at 600 °C, both the device turn-on voltage and on-state resistance increase from 1.08 V and 5.34 mΩ cm² to 1.59 V and 7.1 mΩ cm², respectively. This increase is attributed to the accumulation of Mg and MgO at the Cr₂O₃/Ga₂O₃ interface as observed from the time-of-flight secondary ion mass spectrometry analysis. These findings inform future design strategies of UWBG semiconductor devices for harsh environment operation and underscore the need for further reliability assessments for 𝛽-Ga₂O₃-based devices.

Polycrystalline Ge thin films have attracted considerable attention as potential materials for use in various electronic and optical devices. We recently developed a low-temperature solid-phase crystallization technology for a doped Ge layer and achieved the highest electron mobility in a polycrystalline Ge thin film. In this study, we investigated the effects of strain on the crystalline and electrical properties of n-type polycrystalline Ge layers. By inserting a GeO_x interlayer directly under Ge and selecting substrates with different coefficients of thermal expansion, we modulated the strain in the polycrystalline Ge layer, ranging from approximately 0.6% (tensile) to − 0.8% (compressive). Compressive strain enlarged the grain size to 12 µm, but decreased the electron mobility. The temperature dependence of the electron mobility clarified that changes in the potential barrier height of the grain boundary caused this behavior. Furthermore, we revealed that the behavior of the grain boundary barrier height with respect to strain is opposite for the n- and p-types. This result strongly suggests that this phenomenon is due to the piezoelectric effect. These discoveries will provide guidelines for improving the performance of Ge devices and useful physical knowledge of various polycrystalline semiconductor thin films.

Studying the properties of thermoelectric materials needs substantial effort owing to the interplay of the trade-off relationships among the influential parameters. In view of this issue, artificial intelligence has recently been used to investigate and optimize thermoelectric materials. Here, we used Bayesian optimization to improve the thermoelectric properties of multicomponent III–V materials; this domain warrants comprehensive investigation due to the need to simultaneously control multiple parameters. We designated the figure of merit ZT as the objective function to improve and search for a five-dimensional space comprising the composition of InGaAsSb thin films, dopant concentration, and film-deposition temperatures. After six Bayesian optimization cycles, ZT exhibited an approximately threefold improvement compared to its values obtained in the random initial experimental trials. Additional analysis employing Gaussian process regression elucidated that a high In composition and low substrate temperature were particularly effective at increasing ZT. The optimal substrate temperature (205 °C) demonstrated the potential for depositing InGaAsSb thermoelectric thin films onto plastic substrates. These findings not only promote the development of thermoelectric devices based on III–V semiconductors but also highlight the effectiveness of using Bayesian optimization for multicomponent materials.

Solar-blind photodetectors (SBPDs) based on the ultrawide-bandgap semiconductor Ga₂O₃ have gained attention due to their potential applications in both military and civilian domains. As technology advances, photodetectors are being improved to achieve better energy efficiency, smaller size, and better performance. Solar-blind photodetectors based on a metal-semiconductor-metal structure of amorphous gallium oxide (a-Ga₂O₃) films were fabricated by pulsed magnetron sputtering deposition (PSD). The photodetector based on amorphous gallium oxide has a responsivity of 71.52 A/W, a fast rising and falling response time of less than 200 ms, a photo-to-dark current ratio (PDCR) of 6.52 × 10⁴, and an external quantum efficiency of 34 526.62%. PSD-prepared gallium oxide SBPDs demonstrate a cost-effective room temperature method for growing gallium oxide and show the advantages of growing gallium oxide.

The meta-phase, characterized by crystal-amorphicity duality in the extremely special case, has garnered considerable interests due to its glass-like thermal conductivity and tunable conduction mechanisms for carriers. However, the impact of crystal-amorphicity duality on the electrical and thermal transports remains elusive, and the carrier concentration in the meta-phase is rarely tuned in a wide range for optimized thermoelectric properties. Herein, through a combination of molecular dynamic simulations, chemical bonding analysis, and structural characterization, we reveal the glass-like distribution of Cu cations modulated by the mismatched S/Te anions in Cu_xS_0.6Te_0.4 meta-phase. Such unique atomic structure leads to hopping conduction of carriers and extremely low thermal conductivity. The carrier concentration is effectively optimized by tuning the Cu content in Cu_xS_0.6Te_0.4. Finally, we achieve a high zT of 1.4 at 900 K for Cu_2.01S_0.6Te_0.4 sample, which is three times larger than those of Cu₂S and Cu₂Te matrixes. Remarkably, the high zT value is attained near the Mott–Ioffe–Regel Limit where the carrier mean free path is close to the average atomic distance. Our findings shed light on a new route to discovering high-performance thermoelectric materials.

Capsaicin, a chemical compound present in chili peppers, is widely acknowledged as the main contributor to the spicy and hot sensations encountered during consumption. Elevated levels of capsaicin can result in meals being excessively spicy, potentially leading to health issues, such as skin burning, irritation, increased heart rate and circulation, and discomfort in the gastrointestinal system and even inducing nausea or diarrhea. The level of spiciness that individuals can tolerate may vary, so what may be considered incredibly hot for one person could be mild for another. To ensure food safety, human healthcare, regulatory compliance, and quality control in spicy food products, capsaicin levels must be measured. For these purposes, a reliable and stable sensor is required to quantify the capsaicin level. To leverage the effect of zinc oxide (ZnO), herein, we demonstrated the one-step fabrication process of an electronic tongue (E-Tongue) based on an electrochemical biosensor for the determination of capsaicin. ZnO was electrodeposited on the indium tin oxide (ITO) surface. The biosensor demonstrated the two notable linear ranges from 0.01 to 50 μM and from 50 to 500 μM with a limit of detection (LOD) of 2.1 nM. The present study also included the analysis of real samples, such as green chilis, red chili powder, and dried red chilis, to evaluate their spiciness levels. Furthermore, the E-Tongue exhibited notable degrees of sensitivity, selectivity, and long-term stability for a duration of more than a month. The development of an E-Tongue for capsaicin real-time monitoring as a point-of-care (POC) device has the potential to impact various industries and improve safety, product quality, and healthcare outcomes.

Sustainable production of liquid fuels from abundant resources, such as carbon dioxide and water, may be possible through photoelectrochemical processes. Zinc titanium nitride (ZnTiN₂) has been recently demonstrated as a potential photoelectrode semiconductor for photoelectrochemical fuel generation due to its ideal bandgap induced by cation disorder, shared crystal structure with established semiconductors, and self-passivating surface oxides under carbon dioxide reduction operating conditions. However, substantial improvements in crystalline quality and optoelectronic properties of ZnTiN₂ are needed to enable such applications. In this work, we investigate the heteroepitaxial growth of ZnTiN₂ on c-plane (001) sapphire substrates. Growth on sapphire improves crystal quality, while growth on sapphire at elevated temperatures (300 °C) yields highly-oriented, single-crystal-like ZnTiN₂ films. When Sn is incorporated during these epitaxial growth conditions, notable improvements in ZnTiN₂ film surface roughness and optoelectronic properties are observed. These improvements are attributed to Sn acting as a surfactant during growth and mitigating unintentional impurities such as O and C. The single-crystal-like, 12% Sn-containing ZnTiN₂ films exhibit a steep optical absorption onset at the band gap energy around 2 eV, electrical resistivity of 0.7 Ω cm, and a carrier mobility of 0.046 cm² V⁻¹ s⁻¹ with n-type carrier concentration of 2 × 10²⁰ cm⁻³. Density functional theory calculations reveal that moderate substitution of Sn (12.5% of the cation sites) on energetically-preferred cation sites has negligible impact on the optoelectronic properties of cation-disordered ZnTiN₂. These results are important steps toward achieving high performance PEC devices based on ZnTiN₂ photoelectrodes with efficient photon absorption and photoexcited carrier extraction.

broad application prospects in large-scale flexible electronics. To simplify circuit design and increase integration density, basic complementary circuits require both p- and n-channel transistors based on an individual semiconductor. However, until now, no MOSs that can simultaneously show p- and n-type conduction behavior have been reported. Herein, we demonstrate for the first time that Cu-doped SnO (Cu:SnO) with HfO₂ capping can be employed for high-performance p- and n-channel TFTs. The interstitial Cu⁺ can induce an n-doping effect while restraining electron–electron scatterings by removing conduction band minimum degeneracy. As a result, the Cu_3 atom %:SnO TFTs exhibit a record high electron mobility of 43.8 cm² V^–1 s^–1. Meanwhile, the p-channel devices show an ultrahigh hole mobility of 2.4 cm² V^–1 s^–1. Flexible complementary logics are then established, including an inverter, NAND gates, and NOR gates. Impressively, the inverter exhibits an ultrahigh gain of 302.4 and excellent operational stability and bending reliability.

Due to the lower Auger recombination coefficient of lead salts, the study of room temperature infrared detectors based on lead salt is reemerges as a hot research topic. In this paper, we prepared polycrystalline lead sulfide (PbS) films using chemical bath deposition and fabricated a photovoltage infrared detector with Si. Different from normal PbS photodetectors, which usually show positive photoconductivity, our device demonstrated both positive and negative photoconductivity under 1550 nm laser illumination. The switching of positive and negative photoconductivity was found to be depended on temperature and applied bias. We proposed that the change of photoconductivity is due to the electron traps from S vacancies. Furthermore, we also tested the photoresponse under infrared blackbody radiation, which confirms that the device exhibits high sensitivity. The temperature dependence of PbS infrared photodetector demonstrated in this paper could be useful for applications involving focal array planes based on lead-related materials.

GeSb₂Te₄ (GST124), one of the well-known phase-change materials for nonvolatile memory and rewritable optical storage, has been recently found to be promising thermoelectric materials with low lattice thermal conductivity and high electrical conductivity. However, its thermoelectric performance is greatly restricted by the excessively high hole concentration. Herein, the impact of a series of group IIIA (Al, Ga, In) and group VIA (S, Se) dopants on the electrical transport properties of polycrystalline GST124 has been studied. It is found that element sulfur (S) has the best doping efficiency because the GeS bonds are very strong and ionic that are beneficial for suppressing Ge vacancies to reduce the carrier concentration. Meanwhile, element indium (In) also shows decent doping efficiency because its ionic radius is close to the Ge ion and the InTe bonds have moderate bonding strength. Moreover, In doping introduces a resonant level in the valence band, leading to enhanced Seebeck coefficient and power factor. A high figure of merit (zT)of 0.73 at 700 K and an average zT of 0.48 over 300–750 K are obtained in Ge_0.92In_0.08Sb₂Te₄, which are 26% and 66% higher than pristine GST124. This study will advance the understanding and development of high-performance GeSbTe-based thermoelectric materials.

The discovery of ductile Ag₂(S, Se, Te) materials opens a new avenue toward high-performance flexible/hetero-shaped thermoelectrics. Specifically, the cubic-structured materials are quite attractive by combining remarkable plasticity, decent thermoelectric figure of merit (zT), and no phase transition above room temperature. However, such materials are quite few and the understanding is inadequate on their mechanical and thermoelectric properties. Enlightened by the high-entropy principles, a series of pseudo-ternary Ag₂S-Ag₂Se-Ag₂Te alloys is designed and comprehensive diagrams of composition-structure-plasticity-zT are compiled. Subsequently, the compositional region for the cubic phase is outlined. As a high-entropy example featuring with anion-site alloying and disordered Ag ions, Ag_2-xS_1/3Se_1/3Te_1/3 materials exhibit impressively large elongations of 60–97%, ultralow lattice thermal conductivities of ≈0.2 W m⁻¹ K⁻¹, and decent zT values of 0.45 at 300 K, 0.8 at 460 K. The materials can be readily rolled into thin foils, showing excellent flexibility. Finally, a six-leg in-plane device is fabricated, achieving an output voltage of 13.6 mV, a maximal power of 12.8 µW, and a power density of 14.3 W m⁻² under the temperature difference of 30 K, much higher than the organic counterparts. This study largely enriches the members of cubic ductile inorganic materials for the applications in flexible and hetero-shaped energy and electronic devices.

The use of flashlamp annealing as a low-temperature alternative or supplement to thermal annealing is investigated. Flashlamp annealing and thermal annealing were conducted on 100 nm thick indium tin oxide (ITO) films deposited on glass to compare the properties of films under different annealing methods. The ITO samples had an average initial sheet resistance of 50 Ω/sq. After flashlamp annealing, the sheet resistance was reduced to 33 Ω/sq only, while by thermal annealing at 210 °C for 30 min, a sheet resistance of 29 Ω/sq was achieved. Using a combination of flashlamp annealing and thermal annealing at 155 °C for 5 min, a sheet resistance of 29 Ω/sq was achieved. X-ray diffraction analysis confirmed that flashlamp annealing can be used to crystallize ITO. Flashlamp annealing allows for low-temperature crystallization of ITO on a time scale of 1–3 min. Through electrical and optical characterizations, it was determined that flashlamp annealing can achieve similar electrical and optical properties as thermal annealing. Flashlamp offers the method of low-temperature annealing, which is particularly suitable for temperature sensitive substrates.

The ability of n-type polymer thermoelectric materials to tolerate high doping loading limits further development of n-type polymer conductivity. Herein, two alcohol-soluble n-type polythiophene derivatives that are n-PT3 and n-PT4 are reported. Due to the ability of two polymers to tolerate doping loading more significantly than 100 mol%, both achieve electrical conductivity >100 S cm⁻¹. Moreover, the conductivity of both polythiophenes remains almost constant at high doping concentrations with excellent doping tunability, which may be related to their ability to overcome charging-induced backbone torsion and morphology change caused by saturated doping. The characterizations reveal that n-PT4 has a high doping level and carrier concentration (>3.10 × 10²⁰ cm⁻³), and the carrier concentration continues to increase as the doping concentration increases. In addition, doping leads to improved crystal structure of n-PT4, and the crystallinity does not decrease significantly with increasing doping concentration; even the carrier mobility increases with it. The synergistic effect of these two leads to both n-PT3 and n-PT4 achieving a breakthrough of 100 in conductivity and power factor. The DMlmC-doped n-PT4 achieves a power factor of over 150 µW m⁻¹ K⁻². These values are among the highest for n-type organic thermoelectric materials.

As a common impurity, H plays a role in tuning the electrical properties of β-Ga₂O₃ and has attracted immense interest. Despite years of investigations, the influence of H-doping on electrical properties is not always clear due to the lack of comprehensive characterization on both micro- and macro scale. In this work, we investigate the effects of the H-plasma treatment on the electrical properties of β-Ga₂O₃ films by combining several techniques, from macroscale Hall and photoluminescence measurements to microscale conductive atomic force microscopy (CAFM) and Kelvin probe force microscopy (KPFM). The incorporation of H in β-Ga₂O₃ not only introduces shallow donor states such as H_i, but also passivates V_Ga defects by forming the V_Ga-4H complex. As a result, both the carrier concentration and mobility of H-doped β-Ga₂O₃ film are significantly increased, corresponding to an enhancement of conductivity by four orders of magnitude in comparison with the intrinsic one. These results correlate well with the local conductivity and surface potential mappings obtained from CAFM and KPFM. Moreover, we found that the work function of β-Ga₂O₃ thin films can also be tuned by the H-plasma treatment.

The method to construct the three-dimensional (3D) ordered nanostructure of ZnO for improving its performance has attracted considerable attention and remains a challenging issue, which has theoretical and practical implications for nanoscale applications such as optoelectronics and gas sensors. Herein, we demonstrate a straightforward chemical vapor deposition (CVD) technique for the epitaxial growth of 3D cross-linked comb-like ZnO arrays on r-plane sapphire substrates. The morphological, structural, and optical properties of the as-synthesized samples were examined using X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscopy, Raman spectroscopy, UV–vis spectroscopy, and photoluminescence spectroscopy. A cooperative growth mechanism is suggested to construct 3D cross-linked comb-like ZnO arrays: The supersaturated alloy forms a backbone of oblique nanosails along [101̅0] by the Au-assisted catalytic vapor–liquid–solid (VLS) growth mechanism and the inevitable vapor–solid (VS) lateral extension growth process; simultaneously discrete nanoteeth are grown along the unilateral c-direction [0001] by the Zn self-catalytic VLS mechanism, culminating in a 3D cross-linked array of comb-like ZnO. The development of such a unique 3D cross-linked array allows the exploration of performance in gas-sensitive devices, optoelectronics, and quantum electrical information applications.

Atomic layer deposition (ALD) is a promising coating technology with commercial potential, which can precisely control the film thickness by regulating the deposition cycles. Al-doped zinc oxide (AZO) is regarded as one of the choices for a low-cost substitute for indium tin oxide (ITO) as a transparent conductive material. However, many crystal growth technologies face the problem of lattice mismatch between substrate and film. This study effectively reduced the stress and strain of the film through a pre-deposition process, and compared to the conventional deposition technique, the film has obtained a carrier concentration and mobility of 2.12 × 10¹⁸ cm⁻³ and 38 cm/(V·s), a resistivity of 0.115 Ω/cm. The optical transmittance of AZO films was evaluated using an energy-weighted calculation method based on spectral irradiance, with the average value above 87%.

Photoelectrocatalysis is one of the most promising strategies to address ever-growing wastewater problems. A novel heterojunction photoanode formed by depositing a photocatalyst on a boron-doped diamond (BDD) layer has been considered an ideal material for the practical application of photoelectrocatalytic (PEC) degradation due to its advantages of light responsiveness, excellent charge transport, and robustness. In this study, various BiVO₄/BDD heterojunction photoanodes with different diamond crystalline qualities and electrical conductivities were successfully fabricated by tuning the boron (B) doping concentration of the BDD layer. It was proposed that the charge transport efficiency of the photoanodes is promoted by optimizing the crystalline qualities and electrical conductivities of BDD films, thereby enhancing the PEC activity of the BiVO₄/BDD heterojunction photoanode. Our results suggested that the electrical conductivity of BDD increased and the crystalline quality of BDD deteriorated with increasing B doping concentration. As a result, the PEC activity of the BiVO₄/BDD heterojunction photoanode first increased and then decreased. The optimal PEC activity of the BiVO₄/BDD heterojunction photoanode was achieved corresponding to the [B]/[C] gas ratio at 500 ppm, producing a current density of 3.3 mA/cm² at 1.6 V_RHE (the potential versus a reversible hydrogen electrode) in 0.1 M Na₂SO₄ under AM 1.5 irradiation, which was 1.7 times (1.9 mA/cm²) that of the photoanode with a [B]/[C] gas ratio of 3000 ppm. Meanwhile, the optimized tetracycline hydrochloride (TCH) degradation efficiency was 63.5 % within 9 min (500 ppm gas phase), which was 2.5 times (25.1 %) that of the highly doped photoanode with a [B]/[C] gas ratio of 3000 ppm. This study revealed that the excellent PEC performance benefited from the high crystalline quality and high electrical conductivity of BDD, which depended on the optimized B doping concentration. The idea of enhancing the PEC activity of the photoanode by optimizing the properties of the conductive electrode material proposed in this study provides a conceptual reference for fabricating potential high-performance photoanodes in the future.