Current transport in nonpolar a-plane InN/GaN heterostructures Schottky junction
TL;DR: In this paper, the temperature dependent current transport properties of nonpolar a-plane (112¯0) InN/GaN heterostructure Schottky junction were investigated.
Abstract: The temperature dependent current transport properties of nonpolar a-plane (112¯0) InN/GaN heterostructure Schottky junction were investigated. The barrier height (ϕb) and ideally factor (η) estimated from the thermionic emission (TE) model were found to be temperature dependent in nature. The conventional Richardson plot of the ln(Is/T2) versus 1/kT has two regions: the first region (150–300 K) and the second region (350–500 K). The values of Richardson constant (A*) obtained from this plot are found to be lower than the theoretical value of n-type GaN. The variation in the barrier heights was explained by a double Gaussian distribution with mean barrier height values (ϕb¯) of 1.17 and 0.69 eV with standard deviation (σs) of 0.17 and 0.098 V, respectively. The modified Richardson plot in the temperature range 350–500 K gives the Richardson constant which is close to the theoretical value of n-type GaN. Hence, the current mechanism is explained by TE by assuming the Gaussian distribution of barrier height...
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TL;DR: In this paper, the growth of non-polar III-nitrides has been an important subject due to its potential improvement on the efficiency of III-nodes-based opto-electronic devices.
Abstract: In the last few years, there has been remarkable progress in the development of group III-nitride based materials because of their potential application in fabricating various optoelectronic devices such as light emitting diodes, laser diodes, tandem solar cells and field effect transistors. In order to realize these devices, growth of device quality heterostructures are required. One of the most interesting properties of a semiconductor heterostructure interface is its Schottky barrier height, which is a measure of the mismatch of the energy levels for the majority carriers across the heterojunction interface. Recently, the growth of non-polar III-nitrides has been an important subject due to its potential improvement on the efficiency of III-nitride-based opto-electronic devices. It is well known that the c-axis oriented optoelectronic devices are strongly affected by the intrinsic spontaneous and piezoelectric polarization fields, which results in the low electron-hole recombination efficiency. One of the useful approaches for eliminating the piezoelectric polarization effects is to fabricate nitride-based devices along non-polar and semi-polar directions. Heterostructures grown on these orientations are receiving a lot of focus due to enhanced behaviour. In the present review article discussion has been carried out on the growth of III-nitride binary alloys and properties of GaN/Si, InN/Si, polar InN/GaN, and nonpolar InN/GaN heterostructures followed by studies on band offsets of III-nitride semiconductor heterostructures using the x-ray photoelectron spectroscopy technique. Current transport mechanisms of these heterostructures are also discussed.
56 citations
TL;DR: The deep-level transient spectroscopy results prove the presence of noninteracting point-defect-assisted tunneling, which plays an important role in the transport mechanism of HVPE a-plane GaN Schottky diodes grown via in situ nanodot formation.
Abstract: We investigate the electrical characteristics of Schottky contacts for an Au/hydride vapor phase epitaxy (HVPE) a-plane GaN template grown via in situ GaN nanodot formation. Although the Schottky diodes present excellent rectifying characteristics, their Schottky barrier height and ideality factor are highly dependent upon temperature variation. The relationship between the barrier height, ideality factor, and conventional Richardson plot reveals that the Schottky diodes exhibit an inhomogeneous barrier height, attributed to the interface states between the metal and a-plane GaN film and to point defects within the a-plane GaN layers grown via in situ nanodot formation. Also, we confirm that the current transport mechanism of HVPE a-plane GaN Schottky diodes grown via in situ nanodot formation prefers a thermionic field emission model rather than a thermionic emission (TE) one, implying that Poole⁻Frenkel emission dominates the conduction mechanism over the entire range of measured temperatures. The deep-level transient spectroscopy (DLTS) results prove the presence of noninteracting point-defect-assisted tunneling, which plays an important role in the transport mechanism. These electrical characteristics indicate that this method possesses a great throughput advantage for various applications, compared with Schottky contact to a-plane GaN grown using other methods. We expect that HVPE a-plane GaN Schottky diodes supported by in situ nanodot formation will open further opportunities for the development of nonpolar GaN-based high-performance devices.
17 citations
Cites background from "Current transport in nonpolar a-pla..."
...However, at high temperature, electrons with sufficient energy can ov rcome the high Schottky barrier height, thereby increasing the dominant barrier h ight [26]....
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...However, at high temperature, electrons with sufficient energy can overcome the high Schottky barrier height, thereby increasing the dominant barrier height [26]....
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TL;DR: In this paper, the leakage current and the three main parameter values of diodes (ideality factor n, series resistance Rs, and barrier height ΦB) were found to be very sensitive to temperature changes.
15 citations
TL;DR: In this paper, the barrier characteristics of Pt contacts to relatively highly doped (∼1 × 1018 cm−3) 4H-SiC were investigated using currentvoltage and capacitance-voltage (C-V) measurements in the temperature range of 160-573 K.
Abstract: The barrier characteristics of Pt contacts to relatively highly doped (∼1 × 1018 cm−3) 4H-SiC were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements in the temperature range of 160–573 K. The barrier height and ideally factor estimated from the I-V characteristics based on the thermionic emission model are abnormally temperature-dependent, which can be explained by assuming the presence of a double Gaussian distribution (GD) of inhomogeneous barrier heights. However, in the low temperature region (160–323 K), the obtained mean barrier height according to GD is lower than the actual mean value from C-V measurement. The values of barrier height determined from the thermionic field emission model are well consistent with those from the C-V measurements, which suggest that the current transport process could be modified by electron tunneling at low temperatures.
14 citations
TL;DR: The investigation on deep level transient spectroscopy (DLTS) suggests that non-interacting point-defect-driven tunneling influences the charge transport and paves the way to achieving next-generation optoelectronic applications using Si-based FS-GaN Schottky diodes.
Abstract: In this study, the charge transport mechanism of Pd/Si-based FS-GaN Schottky diodes was investigated. A temperature-dependent current–voltage analysis revealed that the I-V characteristics of the diodes show a good rectifying behavior with a large ratio of 103–105 at the forward to reverse current at ±1 V. The interface states and non-interacting point defect complex between the Pd metal and FS-GaN crystals induced the inhomogeneity of the barrier height and large ideality factors. Furthermore, we revealed that the electronic conduction of the devices prefers the thermionic field emission (TFE) transport, not the thermionic emission (TE) model, over the entire measurement conditions. The investigation on deep level transient spectroscopy (DLTS) suggests that non-interacting point-defect-driven tunneling influences the charge transport. This investigation about charge transport paves the way to achieving next-generation optoelectronic applications using Si-based FS-GaN Schottky diodes.
13 citations
Cites background from "Current transport in nonpolar a-pla..."
...assigns the higher prevailing barrier height to a high temperature [21]....
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...This assigns the higher prevailing barrier height to a high temperature [21]....
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References
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TL;DR: Results suggest that the formation mechanism of the Schottky barrier is locally nonuniform at common, polycrystalline, metal-semiconductor interfaces.
Abstract: A dipole-layer approach is presented, which leads to analytic solutions to the potential and the electronic transport at metal-semiconductor interfaces with arbitrary Schottky-barrier-height profiles. The presence of inhomogeneities in the Schottky-barrier height is shown to lead to a coherent explanation of many anomalies in the experimental results. These results suggest that the formation mechanism of the Schottky barrier is locally nonuniform at common, polycrystalline, metal-semiconductor interfaces.
1,347 citations
TL;DR: In this paper, the ideality factors were obtained to be n∼1.10 and 1.24 eV for the Pd/GaN diode, respectively.
Abstract: Platinum (Pt) and palladium (Pd) Schottky diodes on n‐type GaN grown by metalorganic chemical vapor deposition were achieved and investigated. Aluminum was used for ohmic contacts. Barrier heights were determined to be as high as ΦB=1.13 eV by the current–voltage (I–V) method and ΦB=1.27 eV by the capacitance–voltage (C–V) method for the Pt/GaN diode, and ΦB=1.11 eV, ΦB=0.96 eV, and ΦB=1.24 eV by I–V, activation energy (I–V–T), and C–V methods for the Pd/GaN diode, respectively. The ideality factors were obtained to be n∼1.10.
242 citations
TL;DR: In this paper, two Schottky diodes were fabricated by evaporation of nickel on to an n-type CdF2:YF3 semiconductor and the characteristics of the interface states (energy position, density, time constant and capture cross-section) were obtained for the values of the forward bias in the range 0.0 V ≦V ≦ 0.2 V.
Abstract: Two Schottky diodes were fabricated by evaporation of nickel on to an n-type CdF2:YF3 semiconductor. Diode A was prepared on a slightly etched polished surface and diode B on an unpolished strongly etched surface. The current-voltage (I-V), capacitance-voltage (C-V), and conductance-voltage (G-V) characteristics were determined at room temperature. Both diodes showed non-ideal I-V behaviour with ideality factors 1.5 and 2.0, respectively and are thought to have a metal-interface layer-semiconductor configuration. Under forward bias, the admittance showed large frequency dispersion possibly caused by the interface states in thermal equilibrium with the semiconductor. Analysis of the C-V data in terms of Lehovec's model of an interface state continuum required the supposition of two time constants differing by 2 to 3 orders of magnitude. The characteristic parameters of the interface states (energy position, density, time constant and capture cross-section) were obtained for the values of the forward bias in the range 0.0 V ≦ V ≦ 0.2 V. The diode B is found to have the interface state densities about two orders of magnitude higher than the diode A which may be attributed to the different surface treatments. The C-V measurements at 100 kHz also indicated the presence of a deep donor trap about 0.6 eV below the conduction band edge in diode A.
191 citations
TL;DR: In this paper, the temperature dependence of the electrical properties of Pt∕GaN Schottky barrier has been studied in terms of the existing models on inhomogeneous barriers and correlated to the nanoscale electrical characterization of the barrier.
Abstract: The temperature dependence of the electrical properties of Pt∕GaN Schottky barrier was studied. In particular, a Schottky barrier height of 0.96eV and an ideality factor of 1.16 were found after a postdeposition annealing at 400°C. Nanoscale electrical characterization was carried out by the conductive biased tip of an atomic force microscope both on the bare GaN surface and on the Pt∕GaN contacts. The presence of a lateral inhomogeneity of the Schottky barrier, with a Gaussian distribution of the barrier height values, was demonstrated. Moreover, GaN surface defects were demonstrated to act as local preferential paths for the current conduction. The temperature dependent electrical characteristics of the diodes were discussed in terms of the existing models on inhomogeneous barriers and correlated to the nanoscale electrical characterization of the barrier. In this way, the anomalous electrical behavior of the ideality factor and of the Schottky barrier and the low experimental value of the Richardson’s ...
163 citations
TL;DR: In this paper, the surface effects on metal-silicon contacts have been studied in detail using gate-controlled Schottky-barrier diode structures and it was shown that the generation current in the depletion region often constitutes a significant part of the total reverse current and cannot in general be neglected.
Abstract: Surface effects on metal‐silicon contacts have been studied in detail using gate‐controlled Schottky‐barrier diode structures. The ``excess'' forward and reverse currents at small and moderate bases, respectively, and low breakdown voltages usually associated with metal‐silicon contacts are clearly shown to be due to high fields near the corner region when the surface is accumulated. These currents can be eliminated and breakdown voltage increased by depleting or inverting the surface. By studying the diode characteristics when the surface is inverted, it is shown that the generation current in the depletion region often constitutes a significant part of the total reverse current and cannot in general be neglected.
130 citations