Showing papers on "Schottky barrier published in 1999"

Barrier heights of real Schottky contacts explained by metal-induced gap states and lateral inhomogeneities

Abstract: Most metal–semiconductor contacts are rectifying. For moderately doped semiconductors, the current transport across such Schottky contacts occurs by thermionic emission over the Schottky barrier. The current–voltage characteristics of real Schottky contacts are described by two fitting parameters that are the effective barrier heights ΦBeff and the ideality factors n. Due to lateral inhomogeneities of the barrier height, both parameters differ from one diode to another. However, their variations are correlated in that ΦBeff becomes smaller with increasing n. Extrapolations of such ΦBeff-versus-n plots to the corresponding image-force-controlled ideality factors nif give the barrier heights of laterally homogeneous contacts. They are then compared with the theoretical predictions for ideal Schottky contacts. Data of Si, GaN, GaAs, and CdTe Schottky contacts reveal that the continuum of metal-induced gap states is the fundamental mechanism that determines the barrier heights. However, there are additional b...

Schottky barrier heights of tantalum oxide, barium strontium titanate, lead titanate, and strontium bismuth tantalate

Abstract: The Schottky barrier heights of various metals on the high permitivity oxides tantalum pentoxide, barium strontium titanate, lead zirconate titanate, and strontium bismuth tantalate have been calculated as a function of the metal work function. It is found that these oxides have a dimensionless Schottky barrier pinning factor S of 0.28–0.4 and not close to 1 because S is controlled by Ti–O-type bonds not Sr–O-type bonds, as assumed in earlier work. The band offsets on silicon are asymmetric with a much smaller offset at the conduction band, so that Ta2O5 and barium strontium titanate are relatively poor barriers to electrons on Si.

High-voltage Ni- and Pt-SiC Schottky diodes utilizing metal field plate termination

Abstract: We have fabricated 1 kV 4H and 6H SiC Schottky diodes utilizing a metal-oxide overlap structure for electric field termination. This simple structure when used with a high barrier height metal such as Ni has consistently given us good yield of Schottky diodes with breakdown voltages in excess of 60% of the theoretically calculated value. This paper presents the design considerations, the fabrication procedure, and characterization results for these 1 kV Ni-SiC Schottky diodes. Comparison to similarly fabricated Pt-SiC Schottky diodes is reported. The Ni-SiC ohmic contact formation has been studied using Auger electron spectroscopy and X-ray diffraction. The characterization study includes measurements of current-voltage (I-V) temperature and capacitance-voltage (C-V) temperature characteristics. The high-temperature performance of these diodes has also been investigated. The diodes show good rectifying behavior with ON/OFF current ratios, ranging from 10/sup 6/ to 10 at 27/spl deg/C and in excess of 10/sup 6/ up to 300/spl deg/C.

Spontaneous and piezoelectric polarization effects in III-V nitride heterostructures

Abstract: The role of spontaneous and piezoelectric polarization in III–V nitride heterostructures is investigated Polarization effects and crystal polarity are reviewed in the context of nitride heterostructure materials and device design, and a detailed analysis of their influence in nitride heterostructure field-effect transistors is presented The combined effects of spontaneous and piezoelectric polarization are found to account well for carrier concentrations observed in AlGaN/GaN transistor structures with low to moderate Al concentrations, while the data for higher Al concentrations are consistent with defect formation in the AlGaN barrier Theoretical analysis suggests that incorporation of In into the barrier and/or channel layers can substantially increase polarization charge at the heterojunction interface The use of polarization effects to engineer Schottky barrier structures with large enhancements in barrier height is also discussed, and electrical characteristics of transistors with conventional a

Sub-40 nm ptsi schottky source/drain metal-oxide-semiconductor field-effect transistors

Abstract: PtSi source/drain p-type metal–oxide–semiconductor field-effect transistors (MOSFETs) have been fabricated at sub-40 nm channel lengths with 19 A gate oxide. These devices employ gate-induced field emission through the PtSi ∼0.2 eV hole barrier to achieve current drives of ∼350 μA/μm at 1.2 V supply. Delay times estimated by the CV/I metric extend scaling trends of conventional p-MOSFETs to ∼2 ps. Thermal emission limits on/off current ratios to ∼20–50 in undoped devices at 300 K, while ratios of ∼107 are measured at 77 K. Off-state leakage can be reduced by implanting a thin layer of fully depleted donors beneath the active region to augment the Schottky barrier height or by use of ultrathin silicon-on-insulator substrates.

High voltage (450 V) GaN Schottky rectifiers

Abstract: We fabricated high standoff voltage (450 V) Schottky rectifiers on hydride vapor phase epitaxy grown GaN on sapphire substrate. Several Schottky device geometries were investigated, including lateral geometry with rectangular and circular contacts, mesa devices, and Schottky metal field plate overlapping a SiO2 layer. The best devices were characterized by an ON-state voltage of 4.2 V at a current density of 100 A/cm2 and a saturation current density of 10^–5 A/cm2 at a reverse bias of 100 V. From the measured breakdown voltage we estimated the critical field for electric breakdown in GaN to be (2.2 ± 0.7) × 10^6 V/cm. This value for the critical field is a lower limit since most of the devices exhibited abrupt and premature breakdown associated with corner and edge effects.

Device Physics of Ferroelectric Thin-Film Memories

Abstract: Band structure match-ups are given theoretically from X-ray photoemission spectroscopy (XPS) for the electrode interfaces between platinum electrodes and the ferroelectric thin-film materials commonly used for random access memories (DRAMs and nonvolatile FRAMs): strontium bismuth tantalate (SBT), barium strontium titanate (BST), and lead zirconate titanate (PZT). The results all agree with experimentally measured Schottky barrier heights. The electronegativity constant or S-factor (derivative of Schottky barrier height with respect to electron affinity) is found to be approximately 0.7 for these materials, not the purely ionic value of 1.0. The reduction of a factor of a million in the effective Richardson coefficient is explained. And the paradox of avalanche breakdown but decreasing breakdown fields with increasing temperature is reconciled.

Barrier inhomogeneities and electrical characteristics of Ti/4H-SiC Schottky rectifiers

Abstract: Forward density-voltage (J-V) measurements of titanium/4H-SiC Schottky rectifiers are presented in a large temperature range. While some of the devices present a behavior in accordance with the thermionic current theory, others present an excess forward current at low voltage level. This anomaly appears more or less depending on the rectifier and on the temperature. A model based on two parallel Schottky rectifiers with different barrier heights is presented. The characteristics show good agreement. It is shown that the excess current at low voltage can be explained by a lowering of the Schottky barrier in localized regions. A proposal for the physical origin of these low barrier height areas is given.

Self-Assembled Monolayers as Interfaces for Organic Opto-electronic Devices

Abstract: Charge injection into an organic semiconductor can be improved by using a self-assembled monolayer of functionalized molecules grafted on the electrode. This new interface can be designed in order to reduce the Schottky barrier between the conductive electrode and the organic semiconductor. The polarizability of the molecules involved can also be chosen in order to increase the adhesion of the molecular semiconductor onto the electrode. We present Kelvin Probe experiments and saturated photovoltage measurements performed on a number of such derivatized electrodes. They permit a quantitative description of the potential shifts due to the self-assembled monolayers which are related to the electrical dipoles of the individual molecules constituting them. When conjugated sites contributing to the band states of the organic semiconductor are placed too close to the electrode in the negative part of the image-force potential, two new effects unfavorable to charge injection can appear. We demonstrate that it is convenient to separate the attachment group of the molecule from the conjugated core by a spacer of non-conjugated sites in order to reduce these undesirable effects.

High-resolution Schottky CdTe diode for hard X-ray and gamma-ray astronomy

Abstract: We report a significant improvement of the spectral properties of cadmium telluride (CdTe) detectors, fabricated in the form of a Schottky CdTe diode. With the use of high quality CdTe wafer, we formed a Schottky junction by evaporating indium on the Te-face and operated the detector as a diode. This allows us to apply much higher bias voltage than was possible with the previous CdTe detectors. A 2 mm×2 mm detector of thickness 0.5 mm, when operated at a temperature of 5°C, shows leakage current of only 0.2 and 0.4 nA for an operating voltage of 400 and 800 V, respectively. We found that, at a high-electric field of several kV cm−1, the Schottky CdTe diode has very good energy resolution and stability, suitable for astronomical applications. The broad low-energy tail, often observed in CdTe detectors due to the low mobility and short lifetime of holes, was significantly reduced by the application of a higher bias voltage which improves the charge collection efficiency. We achieved very good FWHM energy resolution of 1.1% and 0.8% at energies 122 and 511 keV, respectively, without any rise time discrimination or pulse height correction electronics. For the detection of hard X-rays and gamma-rays above 100 keV, we have improved the detection efficiency by stacking a number of thin CdTe diodes. Using individual readout electronics for each layer, we obtained high detection efficiency without sacrificing the energy resolution. In this paper, we report the performance of the new CdTe diode and discuss its proposed applications in future hard X-ray and gamma-ray astronomy missions.

A comprehensive thermodynamic analysis of native point defect and dopant solubilities in gallium arsenide

Abstract: A detailed analysis of the role of charged native point defects in controlling the solubility of electrically active dopants in gallium arsenide is presented. The key roles of (a) positively charged arsenic vacancies (VAs+) in determining the doping range over which the solubility curve is linear and (b) multiply negative charged gallium vacancies (VGam−) determining annealing and diffusion behavior in n+ material are demonstrated. An equilibrium thermodynamic model based on these concepts is shown to accurately describe the doping behavior of Te, Zn, Sn, Ge, Si, and C and the formation and annealing of the deep level denoted EL2 (assumed to be the arsenic antisite defect AsGa) in melt- and solution-grown crystals. The model provides a much more comprehensive and accurate description of dopant solubility than the widely cited Schottky barrier model of bulk nonequilibrium dopant incorporation. It is unambiguously shown that partial autocompensation of donor dopants by the donor–gallium vacancy acceptor com...

Direct observation of localized high current densities in GaN films

Abstract: Local high current densities in areas around dislocations with a screw component might be responsible for the observed high leakage currents in GaN-based electronic devices. Using ballistic electron emission microscopy, threading dislocations with a screw component are found to be accompanied by high current densities and low effective Schottky barrier heights. The electronic states responsible for this extremely nonuniform behavior of GaN films are metastable trap states. The experimental results show that acceptor- and donor-like charge traps coexist in the vicinity of dislocations with a screw component.

Semiconductor near-ultraviolet photoelectronics

Abstract: After a brief review of classification, application and sources of near-ultraviolet (UV) radiation the methods for fabricating UV photodetectors and characteristics of the photoconductive cells, p-n junction structure and Schottky barrier photodiodes are discussed. Characteristics of some light filters used in photodetectors and measuring devices are also reported. Now Si p-n structures are commonly used but Schottky diodes based on wide-gap (GaAsP, GaP, GaN, AlGaN, SiC) semiconductors are very attractive. They are insensitive to the infrared radiation and if necessary simple glass filters can be used for correcting the spectrum in such way that it covers just the near-UV region.

Silicon carbide power devices having trench-based silicon carbide charge coupling regions therein

Abstract: Silicon carbide power devices having trench-based charge coupling regions include a silicon carbide substrate having a silicon carbide drift region of first conductivity type (e.g., N-type) and a trench therein at a first face thereof. A uniformly doped silicon carbide charge coupling region of second conductivity type (e.g., an in-situ doped epitaxial P-type region) is also provided in the trench. This charge coupling region forms a P-N rectifying junction with the drift region that extends along a sidewall of the trench. The drift region and charge coupling region are both uniformly doped at equivalent and relatively high net majority carrier doping concentrations (e.g., 1×10 17 cm −3 ) so that both the drift region and charge coupling region can be depleted substantially uniformly when blocking reverse voltages. This combination of preferred drift and charge coupling regions improves the electric field profile in the drift region to such an extent that very low forward on-state drift region resistance can be achieved simultaneously with very high reverse blocking voltage capability. Silicon carbide switching devices that can advantageously use the preferred combination of drift and charge coupling regions include Schottky barrier rectifiers (SBRs), junction field effect transistors (JFETs) and metal-oxide-semiconductor field effect transistors (MOSFETs).

A ballistic electron emission microscopy study of barrier height inhomogeneities introduced in Au/III-V semiconductor Schottky barrier contacts by chemical pretreatments

Abstract: The distribution of Schottky barrier heights over the contact area in Au/III-V semiconductor (GaAs, InP, AlxGa1-xAs, InxGa1-xAs) diodes was determined using ballistic electron emission microscopy. Samples which received a chemical pretreatment in aqueous HF or HCl solutions showed changes in the barrier height distribution. In some cases, short rinses in deionized water could remove these effects. Additional XPS measurements and our former work on Si enabled us to propose a model wherein negatively charged species containing F or Cl at the interface are assumed to be responsible for these changes in barrier height distribution. However, in some cases, these effects were shadowed by more drastic influences due to the chemical processing such as changes in the stoichiometry of the surface region.

Effects of electron confinement on thermionic emission current in a modulation doped heterostructure

Abstract: We discuss mechanisms responsible for the reduction of electron thermionic emission current from a Schottky contact to a modulation doped semiconductor compared to a bulk semiconductor. The effects discussed include metal to semiconductor barrier height enhancement due to proposed electron–electron cloud interaction, confined potential of the reduced dimensional systems, and the reduced dimensional nature of the density of states in the semiconductor. These effects describe the observed lowering of the dark current, and hence noise, of a modulation doped heterojunction based photodetector compared to a conventional bulk device.

Intrinsic electrical properties of Au/SrTiO3 Schottky junctions

Abstract: Intrinsic electrical properties of Au/Nb-doped SrTiO3(001) (STO:Nb) Schottky junctions, fabricated using a proper surface treatment of the STO:Nb and in situ deposition of Au, were investigated in detail. Current–voltage characteristics and photocurrent–wavelength characteristics have shown a temperature-dependent and voltage-dependent Schottky barrier height, while capacitance–voltage characteristics have shown a temperature-independent flat band voltage. Using a temperature-dependent and field-dependent permittivity of the STO in the framework of Devonshire theory, we have performed computer simulation of the Schottky barrier potential to analyze the electrical properties of the junction. It is found that an intrinsic low permittivity layer at the Au/STO:Nb interface explains all the temperature dependence of the electrical properties.

Electrical characteristics of Schottky barriers on 4H-SiC: the effects of barrier height nonuniformity

Abstract: Electrical properties, including current-voltage (I-V) and capacitance-voltage (C-V) characteristics, have been measured on a large number of Ti, Ni, and Pt-based Schottky barrier diodes on 4H-SiC epilayers. Various nonideal behaviors are frequently observed, including ideality factors greater than one, anomalously low I-V barrier heights, and excess leakage currents at low forward bias and in reverse bias. The nonidealities are highly nonuniform across individual wafers and from wafer to wafer. We find a pronounced linear correlation between I-V barrier height and ideality factor for each metal, while C-V barrier heights remain constant. Electron beam induced current (EBIC) imaging strongly suggests that the nonidealities result from localized low barrier height patches. These patches are related to discrete crystal defects, which become visible as recombination centers in the EBIC images. Alternative explanations involving generation-recombination current, uniform interfacial layers, and effects related to the periphery are ruled out.

Analysis of Short-Channel Schottky Source/Drain Metal-Oxide-Semiconductor Field-Effect Transistor on Silicon-on-Insulator Substrate and Demonstration of Sub-50-nm n-type Devices with Metal Gate

Abstract: The Schottky source/drain metal-oxide-semiconductor field-effect transistor (MOSFET) has potential for scaling to the nanometer regime, because low electrode resistances with very shallow extension can be realized using metal source/drain. In this study, very short channel n- and p-type Schottky source/drain MOSFETs with silicon-on-insulator (SOI) structure were analyzed theoretically, and n-type devices were demonstrated experimentally. It was shown theoretically that a drivability of the Schottky source/drain MOSFET comparable to that of conventional MOSFETs can be realized with a low Schottky barrier height. The short-channel effect can be suppressed even with a 15-nm-long channel at tOX = 1 nm and tSOI = 3 nm. The room-temperature operation of sub-50-nm n-type ErSi2 Schottky source/drain MOSFETs on a separation by implanted oxygen (SIMOX) substrate was demonstrated.

Visible and infrared rare-earth-activated electroluminescence from indium tin oxide schottky diodes to gan:er on si

Abstract: Visible and infrared rare-earth-activated electroluminescence (EL) has been obtained from Schottky barrier diodes consisting of indium tin oxide (ITO) contacts on an Er-doped GaN layer grown on Si. The GaN was grown by molecular beam epitaxy on Si substrates using solid sources for Ga, Mg, and Er and a plasma source for N2. RF-sputtered ITO was used for both diode electrodes. The EL spectrum shows two peaks at 537 and 558 nm along with several peaks clustered around 1550 nm. These emission lines correspond to atomic Er transitions to the 4I15/2 ground level and have narrow linewidths. The optical power varies linearly with reverse bias current. The external quantum and power efficiencies of GaN:Er visible light-emitting diodes have been measured, with values of 0.026% and 0.001%, respectively. Significantly higher performance is expected from improvements in the growth process, device design, and packaging.

Schottky energy barriers and charge injection in metal/Alq/metal structures

Abstract: We present internal photoemission, photocurrent versus bias voltage, and current–voltage measurements of metal/tris-(8-hydroxyquinoline) aluminum [Alq]/metal structures. Internal photoemission and photocurrent versus bias measurements were used to determine metal/Alq Schottky energy barriers for a range of contact metals with work functions from 2.7 eV (Sm) to 5.6 eV (Pt). The electron Schottky barrier for low work-function metals ( about 3.6 eV) the ideal Schottky model is generally accurate. A previously established device model was used to describe the current–voltage characteristics using the measured Schottky barriers. The results imply comparable electron and hole mobilities of about 2×10−5 cm2/V s at an electric field of 106 V/cm.

Effects of interfacial oxides on Schottky barrier contacts to n- and p-type GaN

Abstract: Schottky contacts were formed on n- and p-type GaN after either a conventional surface cleaning step in solvents, HCl and HF or with an additional treatment in (NH4)2S to prevent reformation of the native oxide. Reductions in barrier height were observed with the latter treatment, but there was little change in diode ideality factor. A simple model suggests that an interfacial insulating oxide of thickness 1–2 nm was present after conventional cleaning. This oxide has a strong influence on the contact characteristics on both n- and p-type GaN and appears to be responsible for some of the wide spread in contact properties reported in the literature.

On-state and off-state breakdown in GaInAs/InP composite-channel HEMT's with variable GaInAs channel thickness

Abstract: Short-channel Ga/sub 0.47/In/sub 0.53/As high electron mobility transistors (HEMTs) suffer from low breakdown voltages due to enhanced impact-ionization effects in the narrow bandgap channel. This could limit the application of single-channel devices to medium power millimeter-wave systems. A composite Ga/sub 0.47/In/sub 0.53/As/InP channel, which exploits the high electron mobility of Ga/sub 0.47/In/sub 0.53/As at low electric fields, and the low impact-ionization and high electron saturation velocity of InP at high electric fields can overcome this limitation. In this paper we study on-state and off-state breakdown of Ga/sub 0.47/In/sub 0.53/As/InP composite-channel HEMT's with a variable GaInAs channel thickness of 30, 50, and 100 /spl Aring/. Reduction of channel thickness leads to the improvement of both on-state and off-state breakdown voltages. In on-state conditions, the enhancement in the effective Ga/sub 0.47/In/sub 0.53/As channel bandgap that takes place when the channel thickness is reduced to the order of the de Broglie wavelength (channel quantization) effectively enhances the threshold energy for impact-ionization, which is further reduced by real space transfer of electrons from the Ga/sub 0.47/In/sub 0.53/As into the wider bandgap InP. Channel thickness reduction also causes a decrease in the sheet carrier concentration in the extrinsic gate-drain region and therefore, a reduction of the electric field beneath the gate. This, together with the adoption of an Al/sub 0.6/In/sub 0.4/As Schottky layer (increasing the gate Schottky barrier height), leads to excellent values of the gate-drain breakdown voltage. In conclusion, composite channel InAlAs/GaInAs/InP HEMTs, thanks to the combined effect of effective band-gap increase, enhanced real space transfer into InP, and sheet carrier density reduction, allow a good trade-off between current driving capability and both on-state and off-state breakdown voltage.

On the extraction of linear and nonlinear physical parameters in nonideal diodes

Abstract: We describe a parameter extraction technique for the simultaneous determination of physical parameters in nonideal Schottky barrier, p-n and p-i-n diodes. These include the ideality factor, saturation current, barrier height, and linear or nonlinear series, and parallel leakage resistances. The suggested technique which deals with the extraction of bias independent parameters makes use of the forward biased current–voltage (I–V) characteristics and the voltage-dependent differential slope curve α(V)=[d(ln I)]/[d(ln V)]. The method allows (a) establishment of the current flow mechanisms at low and high bias levels, (b) extensive of the permissible ranges of determined parameters beyond what is possible in other published methods, and (c) to automation and computerization of the measurement processes. The method is verified experimentally using metal–semiconductor structures based on Si, InGaP, and HgCdTe as well as an InGaAs/InGaAsP multiple quantum well laser diode exemplifying a p-n junction.

Influence of dioxygen and annealing process on the transport properties of nickel phthalocyanine Schottky-barrier devices

Abstract: Schottky-barrier cells of the type (Al/p-NiPc/Au) are fabricated by successive vacuum depositions of p-NiPc thin films and aluminium fingers onto an ohmic gold electrode. The electrical conductivity has been measured both after exposure to oxygen for 10 days and after annealing at temperature up to 423 K. These cells showed high rectification in the oxygen-doped process. Current density–voltage characteristics under forward bias (aluminium electrode negative) are found to be due to space-charge-limited conduction controlled by a discrete trap level at lower voltage sections and by an exponential distribution of traps at higher voltage regions. Under reverse bias, the conduction processes are interpreted in terms of a transition from electrode-limited Schottky emission to the bulk-limited Poole–Frenkel effect. The effect of annealing showed similar behaviour and resulted in lowering the current density due to oxygen desorption. The linearity of the C −2 –V dependence for oxygen-doped devices is associated with a homogenous distribution of the impurities inside the space-charge region and also provided evidence of uniform doping.

Anomalous current transport in Au/low-doped n-GaAs Schottky barrier diodes at low temperatures

Abstract: The current-voltage characteristics of Au/low-doped n-GaAs Schottky diodes were determined at various temperatures in the range of 77-300 K, The estimated zero-bias barrier height and the ideality factor assuming thermionic emission (TE) show a temperature dependence of these parameters. While the ideality factor was found to show the $T_o$ effect, the zero-bias barrier height was found to exhibit two different trends in the temperature ranges of 77-160 K and 160-300 K, The variation in the Bat-band barrier height with temperature was found to be - (4.7 +/- 0.2) $210^4$ $eVK^1$, approximately equal to that of the energy band gap, The value of the Richardson constant, A**, was found to be $0.27 A cm^-^2 K^-^2$ after considering the temperature dependence of the barrier height. The estimated value of this constant suggested the possibility of an interfacial oxide between the metal and the semiconductor. Investigations suggested the possibility of a thermionic field- emission-dominated current transport with a higher characteristic energy than that predicted by the theory, The observed variation in the zero-bias barrier height and the ideality factor could be explained in terms of barrier height inhomogenities in the Schottky diode.

Numerical study of electrical transport in inhomogeneous Schottky diodes

Abstract: The Poisson equation together with the drift-diffusion equations have been used to simulate both forward and reverse I–V and C–V characteristics of inhomogeneous Schottky diodes. The barrier height distribution has been modeled by a single Gaussian. It is shown that the I–V and C–V curves and consequently extracted apparent Schottky diode parameters depend only slightly, if at all, on a lateral correlation between the single barrier patches in the structure for larger dimension of patches. The apparent barrier height of ordered structures differ only in several thousandths of volt from that of uncorrelated barrier patches. Very small differences were also found between the currents through the diodes with large inhomogeneities and nanosize inhomogeneities. The numerical results show that there is almost no dependence of the current on a pinch-off effect of electric potential. The diminishing of a drift part of the total current in the area of pinched-off potential is probably compensated by a greater diffusion current in the region. Consequently, very small and not unambiguous differences were found between the so called interacting and noninteracting diodes and this division is, according to the above results, questionable.

Method of manufacturing a short-channel FET with Schottky-barrier source and drain contacts

Abstract: The present invention Is a fabrication method for a short-channel Schottky-barrier field-effect transistor device. The method of the present invention includes introducing channel dopants into a semiconductor substrate such that the dopant concentration varies in the vertical direction and is generally constant in the lateral direction. A gate electrode is formed on the semiconductor substrate, and source and drain electrodes are formed on the substrate to form a Schottky or Schottky-like contact to the substrate.

Large Schottky barriers for Ni/p-GaN contacts

Abstract: Large Schottky barriers were measured for Ni contacts formed on low Mg-doped p-GaN. In order to improve leaky Schottky characteristics, low-Mg doping was examined. This provided atomically flat surfaces and a low dislocation density of 5.5×108 cm−2. The Schottky barrier height (qφB) as high as 2.4±0.2 eV and n values of 1.84±0.06 were obtained from current–voltage measurements. These results are in good agreement with the prediction that the sum of qφB of n and p types adds up to the band gap. In the capacitance–voltage measurements, a transient response of capacitance was observed. This indicates that the evaluation of deep levels close to the valence band is possible, which could result in improvement of p-GaN growth.