Metal-semiconductor Interface Research Articles

Role of the Metal-Semiconductor Interface in Halide Perovskite Devices for Radiation Photon Counting.

Halide perovskites are promising optoelectronic semiconductors. For applications in solid-state detectors that operate in low photon flux counting mode, blocking interfaces are essential to minimize the dark current noise. Here, we investigate the interface between methylammonium lead tri-iodide (MAPbI3) single crystals and commonly used high and low work function metals to achieve photon counting capabilities in a solid-state detector. Using scanning photocurrent microscopy, we observe a large Schottky barrier at the MAPbI3/Pb interface, which efficiently blocks dark current. Moreover, the shape of the photocurrent profile indicates that the MAPbI3 single-crystal surface has a deep fermi level close to that of Au. Rationalized by first-principle calculations, we attribute this observation to the defects due to excess iodine on the surface underpinning emergence of deep band-edge states. The photocurrent decay profile yields a charge carrier diffusion length of 10-25 μm. Using this knowledge, we demonstrate a single-crystal MAPbI3 detector that can count single γ-ray photons by producing sharp electrical pulses with a fast rise time of <2 μs. Our study indicates that the interface plays a crucial role in solid-state detectors operating in photon counting mode.

The influence of metallic Bi in BiVO4 semiconductor for artificial photosynthesis

BiVO4 is a non-titania inorganic photocatalyst recognized as an effective visible-light-driven semiconductor that has been shown to be effective for CO2 reduction. However, some characteristics, such as a low separation rate of photogenerated electron-hole pairs and low mobility of electron-hole carriers, are still challenges to the widespread use of this semiconductor. In this paper, the influence of metallic Bi on the CO2 photoreduction activity was evaluated for the BiVO4 semiconductor. Bi–BiVO4 catalysts were prepared by microwave heating at 240 °C, employing different reaction times and magnetic stirring regimes. Metallic Bi improved the catalytic activity of BiVO4 for CO2 reduction, enhancing the absorption of visible light and promoting internal photoemission of electrons in the metal-semiconductor interface, which improves the electron density in the surface of the catalyst. This resulted in an astonishing concentration of methanol; Bi–BiVO4 prepared at 240 °C, for 5 min, and without magnetic stirring, produces around 5.0 mmol L−1 g−1catalyst of methanol and 40 μmol L−1 g−1catalyst of acetone after 240 min of reaction. The mechanism of charge transfer between the BiVO4 and the metallic Bi is influenced by the size of the microsphere crystallites, moreover, the production of methanol increased as the Bi grain size decreased.

Introduction of Graphene to Decrease Barrier Height and Improve Contact Characteristics of Metal/SI-GaAs Interface

The introduction of graphene (Gr) with high thermal conductivity between GaAs and metal electrode can reduce the internal temperature rise and thermal stress accumulation of high-power chips, such as photoconductive switches, protect the contact electrode, and improve the device stability. Meanwhile, the introduction of graphene has the potential to decrease the interface contact resistance. It is valuable to study the effect of graphene on the contact characteristics of the metal–semiconductor interface. The metallic composite Ni/Ge/Au/Ni/Au was obtained by electron beam evaporation, and the graphene was grown by CVD. The current–voltage ( ${I}$ – ${V}$ ) characteristics of the devices over a high-temperature range 300 K–420 K were measured by a semiconductor parameter analyzer. The Schottky barrier properties of metal/semi-insulating GaAs (M/SI-GaAs) with and without graphene interlayer were analyzed by some analysis techniques, such as forward ${I}$ – ${V}$ and Norde’s methods. It was observed that the barrier heights (BHs) were inhomogeneous in the high-temperature range. The mean BHs were extracted by the experimental BH versus 1/T. We found that the homogeneous BH of M/Gr/SI-GaAs was lower that of M/SI-GaAs. It is helpful to improve the performance of semiconductor devices, as we realized the specific contact resistivity lower by two orders of magnitudes via graphene insertion.

Reduced Threshold Voltages and Enhanced Mobilities in Diketopyrrolopyrrole–Dithienothiophene Polymer‐Based Organic Transistor by Interface Engineering

Flexible and low‐power consuming integrated circuits are some of the basic requirements for smart wearable devices. High mobility solution‐processed organic field‐effect transistors (OFETs) have the potential to make a big impact in printed electronic circuits, but their overall performance is currently limited by unusually high threshold voltages (Vth). Herein, systematic optimization of donor–acceptor conjugated polymer, based on dithienothiophene (DTT) and thiophene‐flanked diketopyrrolopyrrole (DPP), namely, PDPPT–DTT, OFETs by application of self‐assembled monolayers (SAMs) at the semiconductor–dielectric, and semiconductor–metal interfaces is reported. The results clearly exhibit that simultaneous application of octyltrichlorosilane (OTS) as semiconductor–dielectric interface modifying layer and pentafluorobenzene thiol (PFBT) as semiconductor–metal interface modifying layer results in significantly lower Vth and subthreshold slope values from −14.07 V and 13.26 (V Dec−1) to +1.06 V and 7.11 (V Dec−1), respectively. This tailored approach is also beneficial in enhancing hole mobility values by an order of magnitude from 0.01 to 0.5 cm2 V−1 s−1 along with the possibility of switching from hole accumulation mode (Vth = −3.75 V) to depletion mode (Vth = +1.06 V) through device engineering. Simultaneous interface engineering reveals OFET electronic properties can be fine‐tuned for robust circuits and low power electronic applications.

Temperature dependence of electrical parameters of the Cu/n-Si metal semiconductor Schottky structures

The main electrical characteristics of Cu/n-Si metal-semiconductor structures have been investigated in the temperature range 50 K to 310 K using current–voltage (I–V) and capacitance–voltage (C–V) measurements. It has been showed that the values of ideality factor and barrier height increase with increase in temperature and are clarified by invoking three different set of Gaussian distributions (GD) of barrier height at 50–160 K, 160–220 K, and 220–310 K. The values of ideality factor and barrier height for the Cu/n-Si metal-semiconductor structures were obtained as 1.435 and 0.487 eV at 50 K, 1.399 and 0.704 at 120 K, 2.192 and 0.701 at 220 K, and 4.286 and 0.759 eV at 310 K, respectively. This results showed fairly that in presence of inhomogeneity at metal semiconductor (MS) interface. The double Gaussian distribution of the temperature dependent I–V characteristics of the Cu/n-Si metal-semiconductor structures barrier diode gave the mean barrier heights of 0.532, 0.638 and 0.816 eV and standard deviations (σo) of 3120 mV, 37 mV and 53 mV, respectively. Thus, the values of the mean barrier height have been verified with the modified ln(I0/T2)−q2σ2/2k2T2 versus (kT)−1 plot which belongs the three different temperature regions. Furthermore, it was showed that a noticeable increase of the saturation current from 1.978 × 10–46 to 3.973 × 10–8 A, (from 50 K to 310 K). The increase in saturation current after temperature was attributed to the presence of interface states created by temperature induced defects.

Effect of Carrier Diffusion on the Optical Property in Si–In–Zn–O/Ag/Si–In–Zn–O Optical Media

Si–In–Zn–O (SIZO)/Ag/Si–In–Zn–O (SIZO) (totally, SAS) multilayered oxide–metal–oxide (OMO) structure has been fabricated and analyzed. Amorphous oxide semiconductor has been uniquely adopted in this study. Different from a metal–dielectric composite multilayer system, carrier diffusion occurred at the semiconductor–metal interface resulting in a complicated electric field distribution in a semiconductor–metal composite multilayer. This phenomenon causes the distortion of bulk permittivity function, therefore mismatching could be found which is confirmed by epsilon-zero-points of samples with different volume filling fraction. Carrier concentration distribution in a SAS was carefully analyzed by introducing Poisson’s electrostatic equation. Further discussion on the distortion of bulk permittivity function in SAS multilayers has been conducted and, carrier diffusion model was introduced to analyze the redistribution of electric field. Carrier concentration dependency of frequency of transmitted light has been investigated and established with a correction parameter related with the total thickness of the samples. It is expected that this research would not only provide a solution to correct the distorted bulk permittivity function of semiconductor–metal multilayer system, but also reveal a potentially promising method for designing a carrier concentration controllable meta-material, such as low-emissivity coating, or low-loss plasmonic for an optical integrated circuits.

Diode-Like Selective Enhancement of Carrier Transport through Metal-Semiconductor Interface Decorated by Monolayer Boron Nitride.

2D semiconductors such as monolayer molybdenum disulfide (MoS2 ) are promising material candidates for next-generation nanoelectronics. However, there are fundamental challenges related to their metal-semiconductor (MS) contacts, which limit the performance potential for practical device applications. In this work, 2D monolayer hexagonal boron nitride (h-BN) is exploited as an ultrathin decorating layer to form a metal-insulator-semiconductor (MIS) contact, and an innovative device architecture is designed as a platform to reveal a novel diode-like selective enhancement of the carrier transport through the MIS contact. The contact resistance is significantly reduced when the electrons are transported from the semiconductor to the metal, but is barely affected when the electrons are transported oppositely. A concept of carrier collection barrier is proposed to interpret this intriguing phenomenon as well as a negative Schottky barrier height obtained from temperature-dependent measurements, and the critical role of the collection barrier at the drain end is shown for the overall transistor performance.

Effects of γ-Ray Irradiation on AlGaN/GaN Heterostructures and High Electron Mobility Transistor Devices

This study examined the effects of three cumulative γ-ray irradiation doses on AlGaN/GaN epilayer material and on high electron mobility transistor (HEMT) devices. After a cumulative γ-ray dose of 16 kGy, the Hall mobility increased from 1800 cm2/V s to 2100 cm2/V s, as determined through Hall measurement. Atomic force microscopy indicated an improvement in surface roughness but no change in the surface potential $$ \left( {\emptyset_{\rm{s}} } \right) $$ . The HEMT device exhibited improvement in the drain current, with a subtle decreasing tendency in the leakage current. At high doses of γ-ray irradiation, the trends in the material and device parameters saturated. Moreover, the metal–semiconductor interface degraded, as confirmed through scanning electron microscopy image analysis.

Enhanced visible-light-driven photocatalytic activity of heterostructure Ag/Bi2MoO6 nanocomposites synthesized by photoreduction method

Heterojunction Ag/Bi2MoO6 nanocomposites with different contents of the loaded Ag nanoparticles were successfully synthesized by photoreduction method. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The analyses certified that the unloaded nanosample was composed of pure orthorhombic Bi2MoO6 nanoplates and that the loaded nanosamples were composed of FCC metallic silver nanoparticles as minor phase on top of orthorhombic Bi2MoO6 nanoplates as major phase. The photocatalytic activities of pure Bi2MoO6 nanoplates and Ag/Bi2MoO6 nanocomposites were investigated through photodegradation of rhodamine B (RhB) and phenol under visible light irradiation. They were found that the Ag/Bi2MoO6 nanocomposites exhibited significant photocatalysis better than pure Bi2MoO6 nanoplates. The enhanced photocatalytic performance of Ag/Bi2MoO6 nanocomposites was ascribed to the formation of Schottky barrier at metal-semiconductor interface.

BSA mediated Ag@Bi2S3 composites: synthesis, characterization, photodegradation of mixed dyes via metal-semiconductor interface, antimicrobial and antioxidant activities

Nowadays, the development of metal-metal sulfide interface semiconductors using green approach is best material for the photocatalytic and biological applications. Here, we provided for the first time, an environmentally friendly route to fabricate bovine serum albumin (BSA) assisted Ag@Bi2S3 composites through a metal-metal sulphide interface via a simple hydrothermal method for the evaluation of photochemical and biological applications. The synthesized composites were characterized by UV–vis DRS, PL, XRD, TEM, and N2 adsorption-desorption isotherms. The UV–vis DRS and PL spectra show that the obtained nano-sized Ag@Bi2S3 composite displays enhanced visible-light absorption and a decreased fluorescence emission compared to that of Bi2S3 nanorods (NRs). The photocatalytic performances of the synthesized composites were evaluated by the degradation of the single (RhB and MB) and mixed dye (RhB+MB) under sunlight irradiation. The results indicated that the Ag@Bi2S3 composite exhibits superior photocatalytic activity (98.38%) than that of individual Ag NPs and Bi2S3 NRs due to the synergistic effect of Ag and Bi2S3 nanophases in the Ag@Bi2S3 composite, which results in an effective charge separation, fast electron transfer from Ag to Bi2S3, and a low recombination of photo-induced electron-hole pairs. The Ag@Bi2S3 composite also has good recycling stability up to 5 cycles and its mechanism also investigated. The evaluation of reactive species during the photocatalytic reaction was also carried out. Further, the effects of Bi2S3 and Ag NPs on the antimicrobial and antioxidant activity of the resultant Ag@Bi2S3 composite were also systematically investigated.

Temperature dependent current–voltage characteristics of Ag/Zn2GeO4/Si diode grown by thermal evaporation method

In this manuscript, we have investigated the transport properties of Ag/Zn2GeO4/Si Schottky diode using temperature dependent current–voltage (I-V) characteristics. The ZnO sample was grown on Si substrate was fabricated by home developed thermal coating unit. The silver (Ag) metal contact of diameters 0.78 mm2 was fabricated on grown Zn2GeO4 and was studied comprehensively using pico meter over temperature range of 120 K–425 K. The I-V data demonstrated that ideality factor decreased from 6.2 to 2.0 and barrier height increased from 0.3 to 0.8 eV as the measurement temperature increased from 120 to 425 K respectively. The data demonstrated the presence of inhomogeneity at the interface of Ag metal and Zn2GeO4 semiconductor. To explain the barrier height inhomogeneity, we have further process the data by plotting different graphs between ideality factor versus barrier height and 1/2kT versus barrier height. The graph between ideality factor and barrier height gives a homogenous barrier height of 0.6 eV. Barrier height versus 1/2kT plot was drawn to obtain the values of mean barrier height for 0.75 eV and standard deviation (δs) 0.016 V at zero bias respectively.

Flexoelectronics of centrosymmetric semiconductors

Interface engineering by local polarization using piezoelectric1-4, pyroelectric5,6 and ferroelectric7-9 effects has attracted considerable attention as a promising approach for tunable electronics/optoelectronics, human-machine interfacing and artificial intelligence. However, this approach has mainly been applied to non-centrosymmetric semiconductors, such as wurtzite-structured ZnO and GaN, limiting its practical applications. Here we demonstrate an electronic regulation mechanism, the flexoelectronics, which is applicable to any semiconductor type, expanding flexoelectricity10-13 to conventional semiconductors such as Si, Ge and GaAs. The inner-crystal polarization potential generated by the flexoelectric field serving as a 'gate' can be used to modulate the metal-semiconductor interface Schottky barrier and further tune charge-carrier transport. We observe a giant flexoelectronic effect in bulk centrosymmetric semiconductors of Si, TiO2 and Nb-SrTiO3 with high strain sensitivity (>2,650), largely outperforming state-of-the-art Si-nanowire strain sensors and even piezoresistive, piezoelectric and ferroelectric nanodevices14. The effect can be used to mechanically switch the electronics in the nanoscale with fast response (<4 ms) and high resolution (~0.78 nm). This opens up the possibility of realizing strain-modulated electronics in centrosymmetric semiconductors, paving the way for local polarization field-controlled electronics and high-performance electromechanical applications.

Structural, optical and photoresponse characteristics of metal-insulator-semiconductor (MIS) type Au/Ni/CeO2/GaN Schottky barrier ultraviolet photodetector

GaN based metal-insulator-semiconductor (MIS) type ultraviolet photodetector was fabricated and investigated using high-k dielectric CeO2 as an insulating oxide layer. Using XRD analysis, the phase formation of the as-deposited CeO2 films on GaN was found to be cubic fluorite. Non-contact mode atomic force microscopy technique was utilized and explored the surface morphology of CeO2 films on GaN composed of prearranged clusters of spherical shape with an average rms surface roughness of 0.428 μm. XPS analysis has revealed the existence of two oxidation states such as Ce3+ and Ce4+ in the Ce3d spectral envelop. Using absorbance versus wavelength data, the Tauc's plot was plotted and calculated a direct optical bandgap of 3.52 eV. The current-voltage (I–V) characteristics extracted from the device revealed the symmetric behavior or formation of back-to-back Schottky barrier at the metal-semiconductor (MS) interface. Photoresponsivity of the device at +10 V bias was calculated as 28.99 A/W and it is higher compared to the values extracted from metal-semiconductor-metal (MSM) type UV PDs reported in the literature. Furthermore, the transient response characteristics of the prepared device showed good stability with almost same rise time and fall time of ~2.73 s and ~5.35 s, respectively. Based on the device performance, the proposed MIS type structure could be a suitable for the development of ultraviolet photodetectors.

Recrystallization effects in GeV Bi ion implanted 4H-SiC Schottky barrier diode investigated by cross-sectional Micro-Raman spectroscopy

It is especially important to study on the change of 4H-SiC physical properties by swift heavy ion irradiation (SHI) for the future application of SiC devices in extreme irradiation environment. Herein, 4H-SiC Schottky barrier diodes (SBDs) are irradiated by 1.9 GeV 209Bi ion beams without intentional heating. The cross-sectional Micro-Raman Spectroscopy (MRS) results clearly indicated that there are new vibration bands at low fluence. This is attributed to the formation of homonuclear bonds Si–Si and C–C within the SiC network to break down the Raman selection rules. At high fluence, there are only typical Raman data for 4H-SiC crystal and the disappearance of Si–Si and C–C bonds. In addition, it is observed that the interfacial structure is modified due to the silicon and carbon atomic migration during SHI process at the metal-semiconductor interface, and then reacting at high temperature annealing treatment. Furthermore, these results suggest that the evolution of recrystallization effect is varied with irradiation fluence by the cross-sectional MRS.

Ga-GaP nanowire hybrid optical system for enhanced coupling, focusing and steering of light

Nanoparticles (NPs) with different geometry have been extensively investigated for several decades owing to their unique optical properties which provide efficient focusing, absorption, scattering, waveguiding and directivity at the nanoscale. The development of an efficient photonic device requires good antenna, as well as resonator properties, that is where hybrid metal-semiconductor nanostructure comes in to play. This work is devoted to the numerical modeling of the optical properties of GaP nanowire (NW) with Ga plasmonic droplet. The modeling results demonstrate that such a self-assembled hybrid nanostructure provides polarization switchable focusing of light at the metal–semiconductor interface, effective beam steering, and emission confinement. Numerical simulation estimates that the field can be focused tenfold at the metal–semiconductor interface providing pathway for excitation of the quantum emitter or hot electron injection. The hybrid structure can also be used to turn the light efficiently without the need to bend the NW acting as a waveguide providing four times more efficient beam steering compare to the NW without the Ga NP. We demonstrate that the light intensity varies 16 times at the interface for S and P polarization which can be utilized for optical switching in photonic or data processing applications. Finally, we discuss the architecture of the devices for the future applications based on the investigated hybrid structure.

Plasmonic Hydrogen Evolution Reactions Driven By Visible Light Illumination at p-Type Semiconductor Electrodes

The efficient control of the visible light driven hydrogen evolution reaction can be recognized as the one of the promising challenge for the sustainable society. It can be said that the wide-band semiconductor electrode is the good material for the photo-energy conversion system. However, various semiconductor electrodes have the limitation to the ultraviolet region because of their wide band gap energy. Recently, plasmoic photoelectric conversion system, which is the combination of the plasmon active metal nano-structures with the semiconductor electrodes, has been received much attention because the system shows the visible light response characters beyond its limitation. In this system, the electrons excited in the metal structures injected into the conduction band of the n-type semiconductor and the remained holes are consumed through the oxidation reaction. Up to now, various plasmon-induced chemical reactions, even the water splitting, have been proposed. As our previous study, we have not only visualized the reaction active sites but also determined the absolute electrochemical potential of the reaction active species through the polymerization reactions of the conductive polymer.1 Although well-established systems have been reported, the direct control of the reduction reaction at the metal-semiconductor interface by the excited electrons has not been well examined. This is because the almost plasmonic photoconversion systems consist of the n-type semiconductor electrode and applied the generated holes to the reactions. In this study, we have tried to establish the plasmon-induced hydrogen evolution system by the introduction of the plasmon-active metal nano-structures into the p-type semiconductor electrodes. By supporting the plasmonic structures, we have confirmed the photo-current generations under the visible light illumination. Through the photocurrent measurements and the incident photon to current conversion efficiency obtained under different pH conditions, we have confirmed the unique pH dependence. In addition to these, we have also investigated the isotopic effect on the hydrogen evolution reaction to clarify the unique surface molecular process.2 Through the various photoelectrochemical measurements, we are sure that our plasmonic hydrogen evolution system could be considered as one of the good candidate for future light energy conversion system.Reference 1. Minamimoto and K. Murakoshi et al., J. Phys. Chem. C., 120(29), 16051 (2016).2. Minamimoto, R. Osaka, and K. Murakoshi, Electrochimica Acta, 304(1), 87 (2019).

Accelerates High Temperature Oxidation due to the Change of Schottky’s Barrier Height of Cr2O3 Layer in Humid Condition

Development of the new generation of Ultra Supercritical (USC) power plant that has successfully achieved the targeted working temperature of 970 K. Nonetheless, increasing the operating temperature will further accelerate the high temperature oxidation of ferritic alloys of the boiler. Furthermore, water vapour in humid environment will make it easier for the alloy to further oxidize at high temperature. It is hypothesized that water vapour provides hydrogen that dissolves into the ferritic alloy susbstrate, hence altering their electronic state at the metal-semiconductor (oxide) interface. This study aims to measure Schottky Barrier Height (SBH) in dry and wet environment and relates it with acclerated oxidation behaviour. The Schottky Barrier was prepared by sputtering Cr2O3 onto the T91 boiler tube in high vacuum condition of 0.4 Pa, RF power 150W for an hour. The existance of Cr2O3 / Fe junction was confirmed by XRD analysis. The junction was then connected with platinum wire to act as the electrode for the current-voltage, I-V and capacitance-voltage, C-V test at high temperature. From the I-V graph, the reversed saturated current, Io was estimated and the SBH was calculated from the results. The SBH increased as the conductivity increased with the increment of temperature. From the C-V plots the value of Vbi was determined and used to calculate the SBH. The SBH increased with the increased of built in voltage. The result obtained from the two method agrees with one another. SBH value in wet condition is higher than that in dry condition. This is explained by the formation of space charge layer at metal/oxide interface due to dissolved hydrogen in metal, thus may change the transport property and accelerate the oxidation rate in water vapor.

Mechanism of Reverse Leakage Current in Schottky Diode Fabricated on Large Bandgap Semiconductors like Ga2O3 or Diamond

One possible mechanism of reverse leakage current in Schottky diodes fabricated on large bandgap semiconductors like Ga2O3 or diamond is Schottky emission (image force barrier lowering) at the metal-semiconductor interface. Historically, there were 2 theories regarding the image force barrier lowering effect. The author’s new idea is that the older and almost forgotten Krömer’s theory can frequently give a much better fit to experimental data for large bandgap semiconductors like Ga2O3 or diamond Schottky diodes. It is possible to define an effective dielectric constant Keff in the reverse leakage current equation and quite frequently 1 ≥ Keff ≥ ¼ for some large bandgap semiconductors like Ga2O3 or diamond. Peripheral surface passivation is important.

Intrinsic Photoconductivity of Few-layered ZrS2 Phototransistors via Multiterminal Measurements

We report intrinsic photoconductivity studies on one of the least examinedlayered compounds, ZrS2.Few-atomic layer ZrS2 field-effect transistorswere fabricated on the Si/SiO2 substrate and photoconductivity measurements were performed using both two- and four-terminal configurationsunder the illumination of 532 nm laser source. We measured photocurrentas a function of the incident optical power at several source-drain (bias)voltages. We observe a significantly large photoconductivity when measured in the multiterminal (four-terminal) configuration compared to thatin the two-terminal configuration. For an incident optical power of 90nW, the estimated photosensitivity and the external quantum efficiency(EQE) measured in two-terminal configuration are 0.5 A/W and 120%,respectively, under a bias voltage of 650 mV. Under the same conditions,the four-terminal measurements result in much higher values for both thephotoresponsivity (R) and EQE to 6 A/W and 1400%, respectively. Thissignificant improvement in photoresponsivity and EQE in the four-terminal configuration may have been influenced by the reduction of contactresistance at the metal-semiconductor interface, which greatly impacts thecarrier mobility of low conducting materials. This suggests that photoconductivity measurements performed through the two-terminal configurationin previous studies on ZrS2 and other 2D materials have severely underestimated the true intrinsic properties of transition metal dichalcogenides andtheir remarkable potential for optoelectronic applications.

Enormous enhancement in electrical performance of few-layered MoTe2 due to Schottky barrier reduction induced by ultraviolet ozone treatment

Doping can improve the band alignment at the metal-semiconductor interface to modify the corresponding Schottky barrier, which is crucial for the realization of high-performance logic components. Here, we systematically investigated a convenient and effective method, ultraviolet ozone treatment, for p-type doping of MoTe2 field-effect transistors to enormously enhance the corresponding electrical performance. The resulted hole concentration and mobility are near 100 times enhanced to be ~ 1.0 × 1013 cm−2 and 101.4 cm2/(V·s), respectively, and the conductivity is improved by 5 orders of magnitude. These values are comparable to the highest ones ever obtained via annealing doping or non-lithographic fabrication methods at room temperature. Compared with the pristine one, the photoresponsivity (522 mA/W) is enhanced approximately 100 times. Such excellent performances can be attributed to the sharply reduced Schottky barrier because of the surface charge transfer from MoTe2 to MoOx (x < 3), as proved by photoemission spectroscopy. Additionally, the p-doped devices exhibit excellent stability in ambient air. Our findings show significant potential in future nanoelectronic and optoelectronic applications.