Increase In Barrier Height Research Articles

Analysis of the carrier transport mechanism and barrier height formation of graphene/Zr–ZnO Schottky contact by I-V-T

The graphene/Zr–ZnO Schottky contacts were prepared by sol-gel method, and the electrical properties of Schottky contact were analyzed by thermionic emission model. The results showed the oxygen vacancies in ZnO films decrease due to Zr ion doping. Meanwhile, the leakage current of graphene/Zr–ZnO Schottky contact reduces and barrier height increases, which is mainly related to the reduction of defect levels at the interface owing to Zr ion doping. By the I-V-T measurement, the result showed that the barrier height increases and the ideal factor decreases with the raising of temperature from 160 K to 300 K, which can be explained by the lateral inhomogeneities of barrier height that was confirmed with gauss distribution function.

Effect of rapid thermal annealing on the electrical properties of dilute GaAsPN based diodes

The effect of rapid thermal annealing on the electrical properties of p++GaP/p−GaAsPN/n+GaP diodes were investigated by using current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) techniques in the temperature range from 100 K to 440 K. It was observed that rapid thermal annealing treatment improves the electrical characteristics of as-grown structures. The annealed samples showed an ideality factor lower than the as-grown samples for all temperatures. The ideality factor values from I-V characteristics has changed between 6.8 and 1.9 in the temperature range of 110–430 K for as grown diode, and between 6.3 and 1.44 in the temperature range 100–400 K for the annealed diode. On the other hand, the barrier height increases and the ideality factor decreases with increasing temperature for all samples. The barrier height values has changed between 0.29 eV and 0.71 eV in the temperature range of 190–430 K for as grown diode, and between 0.38 eV and 0.77 eV in the temperature range 180–420 K for the annealed diode. High values of barrier heights were observed in the annealed samples due to the barrier height in-homogeneities at the p-i-n junction. The net acceptor concentration was calculated to be 1.18 × 1018 cm−3 and 2.11 × 1018 cm−3 for the as-grown and annealed GaAsPN layers, respectively. The net acceptor concentration increases by and the leakage current of the GaAsPN/GaP p-i-n junction decreases by 1–2 orders after RTA. DLTS and Laplace-DLTS measurements reveal three hole traps, H1an(0.06 eV), H2an(0.065 eV) and H3(0.23 eV) in the annealed samples as compared with two hole traps, H4ag(0.07 eV) and H5(0.25 eV) in the as-grown samples. After rapid thermal annealing an extra shallow trap is created.

Investigation of the temperature-dependent electrical properties of Au/PEDOT:WO3/p-Si hybrid device

The electrical properties of Au/PEDOT:WO3/p-Si hybrid devices were studied in terms of current–voltage (I–V) and capacitance–voltage (C–V) measurements. Poly (3,4-ethylene dioxythiophene/tungsten trioxide (PEDOT:WO3) composite was prepared by an in situ chemical oxidative polymerization of monomer in 1-butyl-3-methylimidazoliumtetrafluoroborate (BMIMBF4). Optical and structural properties of the PEDOT:WO3 thin film was characterized by using FTIR, UV–Vis and AFM techniques. The bandgap energy of PEDOT:WO3 thin film was determined as 2.07 eV from UV–Vis spectrum. It was seen that the I–V plots of the Au/PEDOT:WO3/p-Si hybrid devices were non-linear and C−2–V plots were linear in the reverse bias defining rectification behavior. The values of barrier height obtained from the I–V and C−2–V plots of the fabricated devices were found to be 0.729 ± 0.012 eV and 0.817 ± 0.011 eV at room temperature in the dark environment, respectively. Devices have a high rectification behavior with a rectification ratio of 3.645 × 105 at ± 1 V. The temperature-dependent I–V characteristics of one of the devices were also analyzed on the basis of the thermionic emission theory at low forward bias voltage regime. It was observed that the values of ideality factor decrease while the values of barrier height increase with increasing temperature. This kind of temperature dependence was attributed to the presence of the barrier inhomogeneity at the hybrid film/inorganic semiconductor interface. Then, by analysing of the forward bias I–V characteristics at double logarithmic scale, it was seen that the carrier transport in the Au/PEDOT:WO3/p-Si hybrid device demonstrates the space-charge-limited current (SCLC) conduction mechanism controlled by a trap distribution above the valence band edge dominates in the range 0.1–0.3 V voltages. Furthermore, by analyzing the reverse bias I–V–T characteristics, it was shown that Schottky emission was the dominating current conduction mechanism in the temperature range of 240–320 K.

Temperature Dependent Current-Voltage Characteristics of Pt/MoS2 Schottky Junction

AbstractMolybdenum disulphide (MoS2) is one of the transition metal dichalcogenide (TMD) materials which has attracted attention due to its various interesting properties. MoS2 is very promising for electronic and optoelectronic devices due to its indirect band gap (∼1.2 eV) for few layer and direct band gap (∼1.8 eV) for monolayer MoS2. In MoS2 based Schottky devices, Schottky barrier height depends on the thickness of MoS2 because of its tunable electronic properties. Here, we have used DC sputtering technique to fabricate metal-semiconductor junction of MoS2 with platinum (Pt) metal contacts. In this work, MoS2 thin film (∼10 nm) was deposited on p-Silicon (111) using DC sputtering technique at optimized parameters. Schottky metallization of Pt metal (contact area ∼ 0.785x10-2 cm2) was also done using DC sputtering. Current-voltage (I-V) characteristics of the Pt/MoS2 Schottky junction have been investigated in the temperature range 80-350K. Forward I-V characteristics of Pt/MoS2 junction are analysed to calculate different Schottky parameters. Schottky barrier height increases and ideality factor decreases on increasing the temperature from 80-350K. The I-V-T measurements suggest the presence of local inhomogeneities at the Pt/MoS2 junction. Schottky barrier inhomogeneities occur in case of rough interface. In such cases, the Schottky barrier height does not remain constant and vary locally. Current transport through the Schottky junction is a thermally activated process. As temperature increases, more and more electrons overcome the spatially inhomogeneous barrier height. As a result, the ideality factor becomes close to unity and apparent barrier height increases due to increase in temperature.

Electrical and electrochemical behavior of a zinc-rich epoxy coating system with carbon nanotubes as a diode-like material

Non-conventional responses in the impedance spectra of a zinc-rich coating system were observed in electrical and electrochemical impedance measurements that have previously been considered to have no effect on the system. Despite the impressive progress in zinc-rich coating systems to control corrosion in metal structures through galvanic effects, some physical properties influencing the responses of electrochemical systems remain unexplored. Electrochemical and non-electrolytic cells on zinc-rich (55 vol%) coatings with multi-wall carbon nanotube systems were analyzed to determine the intrinsic response of the coating with electrical passive and active analogs under electrical conditioning cycles. In the dry condition, the impedance spectra of the carbon nanotube-added zinc-rich coating showed increased electrical resistance of the film under consecutive cyclic testing. The non-conventional response of the increase in impedance was studied by determining the impedance responses under various temperatures and bias potentials and performing a current-voltage method. The non-conventional phenomenon was found to be caused by an increased barrier height between the semiconducting zinc oxide material and metal, which is susceptible to an external electrical field. During immersion, the change in impedance of the zinc-rich primer (ZRP) film under consecutive electrochemical sequences differed from that under natural degradation. This non-conventional response of the ZRP coating was influenced by the applied bias potential. The capacitive behavior influenced by the zinc corrosion products in the coating had a longer relaxation time, thus decreasing the open circuit potential. To understand this phenomenon, we propose a charging-relaxation potential model. In addition, the potential exhibited a change in the electrical resistance of the ZRP film during consecutive electrochemical testing.

Fermi level depinning in Ti/n-type Ge Schottky junction by the insertion of fluorinated graphene

The effect of fluorinated graphene (f-Gr) as the interfacial layer on Fermi level depinning in Ti/n-type Ge Schottky barrier diodes (SBDs) is intensively studied. Electrical properties of the SBDs are characterized by I-V method. The series resistance, barrier height and ideal factor of the SBDs are extracted by forward I-V, Cheung's method and Norde's method, respectively. Fluorinated graphene is found effective in reducing barrier height of Ti/Ge SBD. On the contrary, the SBD with graphene interlayer shows the increased barrier height and the barrier height changes significantly with bias voltage due to graphene induced Fermi level shift. Therefore, the fluorinated graphene is more stable and predictable in modifying metal/semiconductor interfaces, which can be further used in other metal/semiconductor contacts to achieve high quality SBDs.

Enhanced performance of AlGaN-based ultraviolet light-emitting diodes with linearly graded AlGaN inserting layer in electron blocking layer**Project supported by the National Natural Science Foundation of China (Grant Nos. 61874161 and 11474105), the Science and Technology Program of Guangdong Province, China (Grant No. 2017B010127001), the Science and Technology Project of Shenzhen City, China (Grant No. GJHZ20180416164721073), and the Education Department Project

The conventional stationary Al content AlGaN electron blocking layer (EBL) in ultraviolet light-emitting diode (UV LED) is optimized by employing a linearly graded AlGaN inserting layer which is 2.0 nm Al0.3Ga0.7N/5.0 nm AlxGa1−xN/8.0 nm Al0.3Ga0.7N with decreasing value of x. The results indicate that the internal quantum efficiency is significantly improved and the efficiency droop is mitigated by using the proposed structure. These improvements are attributed to the increase of the effective barrier height for electrons and the reduction of the effective barrier height for holes, which result in an increased hole injection efficiency and a decreased electron leakage into the p-type region. In addition, the linearly graded AlGaN inserting layer can generate more holes in EBL due to the polarization-induced hole doping and a tunneling effect probably occurs to enhance the hole transportation to the active regions, which will be beneficial to the radiative recombination.

Rectifying and breakdown voltage enhancement of Au/n-GaN Schottky diode with Al-doped ZnO films and its structural characterization

Radio frequency magnetron sputtered Al-doped zinc oxide (AZO) thin films were formed on n-type gallium nitride (GaN). X-ray diffraction reflections and Raman modes confirmed the formation of the AZO films. The optical band gap of the deposited AZO film was found to be 3.31 eV and exhibited a fairly smooth surface and continuous growth across the surface with a grainy structure. The Au/AZO/n-GaN heterojunction Schottky diode was fabricated and investigated the influence of the presence of AZO layer in Au/n-GaN Schottky diode, characterizing its electrical and breakdown voltage properties. The AZO layer led to an excellent improvement in the rectifying behavior with an increase in barrier height of the Au/n-GaN Schottky diode from 0.69 to 0.90 eV. Reverse breakdown voltage of the Au/n-GaN Schottky diode and Au/AZO/n-GaN heterojunction diode were obtained to be 86 and 232 V, respectively, without any edge termination methods. The AZO layer effectively reduced the interface states in the Au/n-GaN Schottky diodes. Schottky and Poole-Frenkel emission mechanisms dominated the reverse current in Au/n-GaN Schottky diode and Au/AZO/n-GaN heterojunciton diode, respectively. The results signify the importance of the metal-insulator-semiconductor structure and in particular the AZO layer in reducing the leakage current and improving the device performance. A further improvement in breakdown voltage can be achieved by employing field plate and guard-ring structures for edge termination.

Modified approach to modeling barrier inhomogeneity in Schottky diodes

The conventional model describing barrier inhomogeneities in Schottky diodes with a single series resistance leads to many anomalies including crossing over effect in current–voltage–temperature (I–V–T) plots. A new model is therefore proposed here which entails a parallel combination of several diodes, each with its own series resistance. Further, the barrier heights follow a Gaussian distribution function ρ(φ) with a mean barrier height and standard deviation σ. The series resistance is believed to vary inversely with the ρ(φ) value of the concerned barrier height and hence the area occupied. The occurrence of anomalies with the conventional model is examined in depth, and their effective elimination with the proposed model is discussed with the undertaken current simulations. In addition to predicting the increase in apparent barrier height with increase in temperature, decrease in ideality factor with increase in temperature, and elimination of modeling anomalies observed in the conventional model, the model is successful in predicting that apparent barrier height as a function of inverse thermal energy is a quadratic behavior even with a single distribution. This previously required unlikely scenarios involving multiple mean barrier heights and standard deviations with the conventional model. Finally, the description also explains the observed increase in the apparent barrier height with decrease in temperature of a Schottky diode when the values are deduced from the C–V–T data under reverse bias.

Conduction mechanisms of the reverse leakage current of 4H-SiC Schottky barrier diodes

A new numerical method for determining the reverse transition voltage between thermionic and tunneling mechanisms has been performed for 4H-SiC Schottky barrier diodes. The idea of this method is based on equality between thermionic emission and the tunneling process and both are combined with the barrier lowering model. Application of this method shows a strong discrepancy between our results and those deduced from Padovani-Stratton conditions. The reverse transition voltage versus the temperature plot exhibits an unexpected peak at low temperatures which means that the thermionic emission mechanism predominates at low temperatures. The reverse transition voltage increases linearly with the increase in barrier height, the effective mass and the inverse of doping concentration. In order to predict the reverse transition voltage as a function of temperature, doping concentration and barrier height for a 4H-SiC Schottky barrier diode, an analytical model has been proposed.

Strain-induced changes in AlGaN/GaN two-dimensional electron gas structures with low surface state densities

We report on the effects of applied external strain on AlGaN/GaN two dimensional electron gas structures exhibiting a negative strain dependence of the sheet carrier density (ns). Flexible AlGaN/GaN heterojunctions, grown on two-dimensional boron nitride (BN)-on-sapphire templates, were released from the substrate via strain-induced separation at the weak BN van der Waals interface and then transferred to flexible substrates. By releasing the AlGaN/GaN layer from the substrate, residual strain was removed which allowed for isolation and study of the effects of the externally applied strain. By bending samples, uniaxial strain up to 0.15% was applied as measured by the shifts in the GaN E2H Raman mode. Hall effect measurements revealed a 2.5% decrease in ns with 0.11% applied tensile strain, which is contrary to the increase expected from the piezoelectric effect. The observed decrease in ns is attributed to a relatively large increase in the AlGaN surface barrier height. This effect, which is rarely reported, is observable due to a low surface state density (2.2 × 1012 cm−2 eV–1) in the samples. Illumination was found to dramatically alter the ns-strain dependence, an effect potentially related to detrapping of electrons in the GaN buffer.

Influence of the tensor force on the microscopic heavy-ion interaction potential

Background: The tensor interaction is known to play an important role in the nuclear structure studies of exotic nuclei. However, most microscopic studies of low-energy nuclear reactions neglect the tensor force, resulting in a lack of knowledge concerning the effect of the tensor force on HIC...... Purpose: The theoretical study of the influence of the tensor force on heavy-ion interaction potentials is required to further our understanding of the microscopic mechanisms entailed in fusion dynamics. Method: The full Skyrme tensor force is implemented into the static Hartree-Fock and dynamic density-constrained time-dependent Hartree-Fock (DC-TDHF) theory to calculate both static (frozen density) and dynamic microscopic interaction potentials for reactions involving exotic and stable nuclei. Results: The static potentials are found to be systematically higher than the dynamical results, which are attributed to the microscopic dynamical effects included in TDHF. We also show that the dynamical potential barriers vary more significantly by the inclusion of tensor force than the static barriers. The influence of isoscalar and isovector tensor terms is also investigated with the TIJ set of forces. For light systems, the tensor force is found to have an imperceptible effect on the nucleus-nucleus potential. However, for medium and heavy spin-unsaturated reactions, the potentials may change from a fraction of an MeV to almost 2 MeV by the inclusion of tensor force, indicating a strong impact of the tensor force on sub-barrier fusion. Conclusions: The tensor force could indeed play a large role in the fusion of nuclei, with spin-unsaturated systems seeing a systematic increase in ion-ion barrier height and width. This fusion hindrance is partly due to static, ground state effects from the inclusion of the tensor force, though additional hindrance appears when studying nuclear dynamics.

Numerical Study of Noise Barriers’ Side Edge Effects on Pollutant Dispersion near Roadside under Various Thermal Stability Conditions

Roadside noise barrier helps to reduce downwind pollutant concentrations from vehicle emission. This positive characteristic of the construction feature can be explained by its interaction with flow distribution and species dispersion. In this paper, a three-dimensional numerical model has been developed to simulate highway pollutant dispersion—a realizable k-ε model was employed to model turbulent flow, and a non-reaction species dispersion model was applied to simulate species transport. First, numerical models were validated with experimental data, and good agreement was observed. Then, detailed simulations were conducted to study double barriers’ effects on highway pollutant dispersion under different settings: noise barriers with different heights, noise barriers with and without edge effects, and different atmospheric thermal boundary conditions. Results show that: (1) Noise barriers without edge effects cause bigger downwind velocity and turbulence intensity than noise barriers with edge effects. (2) At ground level, lower downwind pollutant concentration and higher pollutant concentration, near upwind barrier and between barriers, are observed for noise barriers without edge effect cases; higher on-road pollutant concentration can be seen near barrier side edges for cases with edge effect. (3) Downwind velocity and turbulence intensity increase as barrier height increases, which causes reduced downwind pollutant concentration. (4) With the same barrier height, under unstable atmospheric boundary condition, the lowest pollutant concentration can be found for both downwind and between barriers. Overall, these findings will provide valuable inputs to noise barrier design, so as to improve roadside neighborhood air quality.

Impact of MoS2 layer transfer on electrostatics of MoS2/SiO2 interface

Using internal photoemission of electrons from few-monolayer thin MoS2 films into SiO2 we found that the MoS2 layer transfer processing perturbs electroneutrality of the interface, leading to an increase of the electron barrier height by ≈0.5–1 eV as compared to the case of the same films synthesized directly on SiO2. This effect is associated with the formation of an interface dipole, tentatively ascribed to interaction of H2O molecules with the SiO2 surface resulting in the incorporation of silanol (SiOH) groups. This violation of the interface electroneutrality may account for additional electron scattering in ultrathin transferred films and threshold voltage instabilities. Post-transfer annealing in H2S is shown to reduce the transfer-induced interface degradation.

Schottky Nature of Au/SnO2 Ultrathin Film Diode Fabricated Using Sol–Gel Process

In this letter, sol-gel-processed SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> films were deposited, with thicknesses varying from 3.5 to 5.0 nm, by controlling the concentration of the precursor solutions. Through electrical and spectroscopic investigations, it was found that the optical energy bandgap and the electron affinity were affected by the quantum confinement effect and Burstein-Moss effect. Moreover, the increased barrier height between Au and SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> semiconductors was enhanced when thinner SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layers were used, resulting in strong Schottky diode characteristics. This letter allows one to examine the size scaling effects of ultrathin electrical devices with SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> channel layers. In addition, a generalized energy band diagram derived from the bandgap broadening in ultrathin SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> semiconductors is presented, which will allow the elucidation of the carrier transport mechanism and optical properties of quantum confined SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> semiconductor-based optical and electrical devices.

β-Ga2O3-based metal–oxide–semiconductor photodiodes with HfO2 as oxide

We proposed β-Ga2O3-based metal–oxide–semiconductor (MOS) photodiodes using HfO2 as the oxide. Because of the larger band gap of HfO2 than that of β-Ga2O3 and the type-II band alignment at the HfO2/β-Ga2O3 interface, the MOS photodiodes exhibited almost no reduction in photoresponsivity against 254 nm light near zero external bias compared with Schottky photodiodes. In contrast, reverse leakage currents of the MOS photodiodes were substantially decreased compared with Schottky photodiodes owing to the increase in the apparent barrier height between the metal and the semiconductor. These features of the MOS photodiodes are beneficial for the future development of β-Ga2O3-based avalanche photodiodes without p–n junctions.

The Effect of Base–Emitter Interfacial Layer on the Organic Permeable Base Transistor’s Characteristics

ABSTRACTA thin interfacial layer of 20 nm has been introduced to increase the barrier from 0.9 to 1.1 eV or 1.2 eV or 1.4 eV between the base and emitter of an organic permeable base transistor (OPBT). The effect of this barrier height has been studied through the OPBTs fabricated with 5,5′′′′′-dihexyl-2,2′:5′,2′′:5′′,2′′′:5′′′,2′′′′:5′′′′,2′′′′′-sexithiophene as an active material for forming emitter and collector regions. First time, it has been observed that output characteristics of OPBT’s mimics the near-ideal characteristics of the metal oxide semiconductor field effect transistor and experiences significant change as the barrier height increases and the device enters into the velocity saturation region at lower applied voltage. The gain factor (β) has been found to vary from 0.5 to 2.7 µAV–2 with the increase in the barrier from 0.9 to 1.2 eV while at the high barrier of 1.4 eV, it is almost negligible.

Reaction mechanisms and kinetics of the β-elimination processes of compounds CHF2CH2SiFnMe3–n (n = 0–3): DFT and CBS-QB3 methods using Rice-Ramsperger-Kassel-Marcus and transition state theories

The gas-phase β-elimination kinetics of 2,2-difluoroethyltrifluorosilane (1), 2,2-difluoroethylmethyldifluorosilane (2), 2,2-difluoroethyldimethylfluorosilane (3), and 2,2-difluoroethyltrimethylsilane (4) have been investigated computationally using M06-2x exchange-correlation functional as well as the benchmark CBS-QB3 quantum chemical approach. The obtained energy profile has been enhanced with kinetic calculations using statistical Rice-Ramsperger-Kassel-Marcus (RRKM) theory and transition state theory (TST). The calculated results are in good agreement with the available experimental data which obtained by the CBS-QB3 approach. The comparison between all our calculations and experiments indicates that a thermodynamically-controlled reaction that gives more stable products derived from the compound 2 species will be the vinyl fluoride and methyltrifluorosilane species, whereas the elimination of compound 1 into the vinyl fluoride and silicon tetrafluoride species is favorable process from kinetic point of view.In proportion to rather larger barrier heights, pressures where P > 10―4 bar are insufficient to ensure a saturation of the calculated rate constant compared with the RRKM unimolecular rate kinetics (in high-pressure limit).Natural bond orbital analysis revealed that in accordance with an increase of barrier height from compounds 1 to 4, the HOMO-LUMO energy-gaps decreases. Furthermore, the obtained order of barrier heights could be explained by the number of electron-withdrawing fluorine atoms attached to the silicon atom. The occupancies of σC1―F3 bonding orbital for the studied compounds are as follows: 1>2>3>4 and those of σ*C1―F3 antibonding orbital increase in the opposite order (4>3>2>1) by NBO analysis. This fact explains a comparatively easier elimination of the σC1―F3 bond in compound 1 compared to the other compounds. The calculated data reveal that the polarization of the C1―F3 bond in the sense C1δ+–F3δ− is the determining factor in the elimination reaction of the studied compounds.

Intrinsic Performance of Germanane Schottky Barrier Field-Effect Transistors

Germanane (GeH), a hydrogenated germanium monolayer, is a new family of 2-D semiconductors, exhibiting promising potential for electronic device applications. Here, we investigate GeH Schottky barrier (SB) field-effect transistors (FETs) using atomistic quantum transport simulations. Our simulation results reveal that the ohmic-contact device with zero SB height ( $\Phi _{\text {Bn}}$ ) exhibits ~20% lower ON-current than the metal-oxide-semiconductor (MOS) FET counterpart due to the inherent tunnel barrier at the metal–semiconductor junction. We also compare 14-nm-channel GeH and black phosphorus (BP) SBFETs with a finite SB height of $\Phi _{\text {Bn}} = 0.22$ eV for both devices. Our results show that GeH outperforms BP in the ON-state, but it can suffer from larger leakage current in the OFF-state. We further investigate the effect of barrier height in GeH SBFET by varying $\Phi _{\text {Bn}}$ from 0 eV to a half bandgap (0.78 eV). In general, as barrier height increases, both ON-current and the minimum leakage current are reduced. It is also observed that, with increasing SB height, intrinsic delay increases but the required energy per switching decreases, indicating the trade-off between the device speed and the energy dissipation. Our benchmarking of GeH SBFET against GeH and BP MOSFETs demonstrates that GeH generally outperforms BP in terms of energy-delay product (EDP). By performing careful engineering of SB height along with the device threshold voltage, we show that the minimum EDP of GeH SBFET can be as comparable as that of the MOSFET counterpart, suggesting great potential of GeH SBFETs for future switching device applications.

Effect of surface treatments on electrical properties of β-Ga2O3

The effect of various combinations of gaseous (ultraviolet/O3), liquid (HCl, buffered oxide etch, and H2O2), or plasma (CF4 and O2) treatments of the surface of β-Ga2O3 was quantified by current–voltage and capacitance–voltage measurements of rectifier structures. Plasma exposure (13.56 MHz, 24 kW/cm2) always led to significant degradation of the surface, as evidenced by large increases in rectifier reverse current and ideality factor (from 1.01 in control samples to ∼3.8 in plasma exposed samples, indicating additional defect-related carrier transport mechanisms) and lowering of the Schottky barrier height (from 1.21 eV in control samples to 0.75–0.86 eV in plasma exposed samples) and diode rectification ratio, with degraded reverse recovery characteristics. This was true of both CF4 and O2, even though it is known that fluorine incorporation in the near-surface leads to donor compensation and an increase in barrier height. Damage from the plasma exposure was not fully recovered by annealing at 500 °C. The O3 and liquid chemical cleans did lead to reduced reverse current in rectifiers, with no measurable decrease in barrier height, increase in ideality factor, or degradation of reverse recovery characteristics. Surfaces treated in this manner did not significantly change for anneals up to 500 °C; however, the Ni/Au contacts already show degradation after annealing at 350 °C.