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1.
Recently GaN-based high electron mobility transistors (HEMTs) have
revealed the superior properties of a high breakdown field and high
electron saturation velocity. Reduction of the gate leakage current
is one of the key issues to be solved for their further improvement.
This paper reports that an Al layer as thin as 3 nm was inserted
between the conventional Ni/Au Schottky contact and n-GaN epilayers,
and the Schottky behaviour of Al/Ni/Au contact was investigated
under various annealing conditions by current--voltage (I--V)
measurements. A non-linear fitting method was used to extract the
contact parameters from the I--V characteristic curves.
Experimental results indicate that reduction of the gate leakage
current by as much as four orders of magnitude was successfully
recorded by thermal annealing. And high quality Schottky contact
with a barrier height of 0.875 eV and the lowest reverse-bias
leakage current, respectively, can be obtained under 12 min
annealing at 450°C in N2 ambience. 相似文献
2.
Performance comparison of Pt/Au and Ni/Au Schottky contacts on AlxGa1-x N/GaN heterostructures at high temperatures
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In contrast with Au/Ni/Al 0.25 Ga 0.75 N/GaN Schottky contacts,this paper systematically investigates the effect of thermal annealing of Au/Pt/Al 0.25 Ga 0.75 N/GaN structures on electrical properties of the two-dimensional electron gas in Al 0.25 Ga 0.75 N/GaN heterostructures by means of temperature-dependent Hall and temperature-dependent current-voltage measurements.The two-dimensional electron gas density of the samples with Pt cap layer increases after annealing in N 2 ambience at 600℃ while the annealing treatment has little effect on the two-dimensional electron gas mobility in comparison with the samples with Ni cap layer.The experimental results indicate that the Au/Pt/Al 0.25 Ga 0.75 N/GaN Schottky contacts reduce the reverse leakage current density at high annealing temperatures of 400-600℃.As a conclusion,the better thermal stability of the Au/Pt/Al 0.25 Ga 0.75 N/GaN Schottky contacts than the Au/Ni/Al 0.25 Ga 0.75 N/GaN Schottky contacts at high temperatures can be attributed to the inertness of the interface between Pt and AlxGa1-xN. 相似文献
3.
Fundamentals of the Schottky contacts and the
high-temperature current conduction through three kinds of Schottky
diodes are studied. N-Si Schottky diodes, GaN Schottky diodes and
AlGaN/GaN Schottky diodes are investigated by I--V--T
measurements ranging from 300 to 523~K. For these Schottky diodes, a
rise in temperature is accompanied with an increase in barrier
height and a reduction in ideality factor. Mechanisms are
suggested, including thermionic emission, field emission,
trap-assisted tunnelling and so on. The most remarkable finding in
the present paper is that these three kinds of Schottky diodes are
revealed to have different behaviours of high-temperature reverse
currents. For the n-Si Schottky diode, a rise in temperature is
accompanied by an increase in reverse current. The reverse current
of the GaN Schottky diode decreases first and then increases with
rising temperature. The AlGaN/GaN Schottky diode has a trend
opposite to that of the GaN Schottky diode, and the dominant
mechanisms are the effects of the piezoelectric polarization field and
variation of two-dimensional electron gas charge density. 相似文献
4.
Using polarization field effect-based thermionic field emission (PFE-TFE) model based on current–voltage–temperature data, possible carrier transport mechanisms for Pt/Au and Cr/Pd Schottky contacts to Al0.25Ga0.75N/GaN layers were investigated. Thermionic emission (TE) model was also investigated to compare to the PFE-TFE. It was shown that Schottky barrier heights (SBHs) are significantly affected by a polarization field-induced carrier density of the AlGaN layer. In addition, relatively little temperature dependence on the leakage current density of both contacts was found, which is in good agreement with the PFE-TFE model. The results indicate that the TFE is responsible for the current flow across the metal/AlGaN–GaN interface at T ≥ 293 K. 相似文献
5.
Electrical devices involve different types of diode in prospective electronics is of great importance. In this study, p-type Si surface was covered with thin film of TiO2 dispersion in H2O to construct p-Si/TiO2/Al Schottky barrier diode (D1) and the other one with TiO2 dispersion doped with zirconium to construct p-Si/TiO2-Zr/Al diode (D2) by drop-casting method in the same conditions. Electrical properties of as-prepared diodes and effect of zirconium as a dopant were investigated. Current–voltage (I–V) characteristics of these devices were measured at ambient conditions. Some parameters including ideality factor (n), barrier height (ΦB0), series resistance (Rs) and interface state density (Nss) were calculated from I–V behaviours of diodes. Structural comparisons were based on SEM and EDX measurements. Experimental results indicated that electrical parameters of p-Si/TiO2/Al Schottky device were influenced by the zirconium dopant in TiO2. 相似文献
6.
Organic solar cells using the CuPc and PTCBI semiconductor layers were studied. A high open circuit voltage of 1.15 V was
obtained in a device with ITO/PEDOT:PSS/CuPc (15 nm)/PTCBI (7 nm)/Al structure. Results were interpreted in terms of a modified
CuPc-Al Schottky diode for the thin PTCBI case and a CuPc-PTCBI heterojunction for the thick PTCBI case. Also, the formation
of a thin aluminum oxide layer under the aluminum electrode was postulated. This layer has a beneficial aspect wherein shunting
losses are reduced and a high photovoltage is enabled. However, it adds greatly to the series resistance to a point where
the short circuit current density is reduced. CuPc Schottky diodes with an ITO/PEDOT:PSS/CuPc/Al structure yielded a high
V
oc of 900 mV for a CuPc layer of thickness 140 nm. The V
oc increased with increase in CuPc layer thickness. 相似文献
7.
D. C. Oh A. Setiawan J. J. Kim H. J. Ko H. Makino T. Hanada M. W. Cho T. Yao 《Current Applied Physics》2004,4(6):625-629
We investigated the optical properties and electrical properties of N-doped ZnO layers grown on (0 0 0 1) GaN/Al2O3 substrates by molecular beam epitaxy, employing 10 K photoluminescence (PL) measurements, current–voltage (IV) measurements, capacitance–voltage (CV) measurements, and 100 K photocapacitance (PHCAP) measurements. 10 K PL spectra showed that excitonic emission is dominant in N-doped ZnO layers grown after O-plasma exposure, while overall PL emission intensity is significantly reduced and deep level emission at around 2.0 2.2 eV is dominant in N-doped ZnO layers grown after Zn exposure. IV and CV measurements showed that N-doped ZnO layers grown after Zn exposure have better Schottky diode characteristics than O-plasma exposed samples, and an N-doped ZnO layer grown at 300 °C after Zn exposure has best Schottky diode characteristics. This phenomenon is presumably due to lowered background electron concentration induced by the incorporation of N. PHCAP measurements for the N-doped ZnO layer revealed several midgap trap centers at 1.2 1.8 eV below conduction band minimum. 相似文献
8.
采用60Co γ射线源对高铝组分Al0.5Ga0.5N盲紫外p-i-n结构光探测器和Si基可见光p-i-n结构探测器进行了累计剂量分别为0.1, 1, 10 Mrad(Si)总剂量辐照实验. 实验发现, 随着辐照剂量的增加, AlGaN盲紫外p-i-n结构光探测器的理想因子显著增大, 辐照后理想因子n > 2; 而Si基可见光p-i-n 结构探测器的理想因子随辐照剂量的变化并不明显. AlGaN盲紫外p-i-n结构光探测器理想因子的退化可能主要是因为欧姆接触性能的退化, Si基可见光p-i-n结构探测器的理想因子的变化则可能是由于敏感层的退化.
关键词:
xGa1?xN')" href="#">高铝组分AlxGa1?xN
γ射线辐射效应
理想因子
欧姆接触 相似文献
9.
Fuxue WangHai Lu Xiangqian XiuDunjun Chen Ping HanRong Zhang Youdou Zheng 《Applied Surface Science》2011,257(9):3948-3951
The effect of oxygen plasma treatment on the performance of GaN Schottky barrier diodes is studied. The GaN surface is intentionally exposed to oxygen plasma generated in an inductively coupled plasma etching system before Schottky metal deposition. The reverse leakage current of the treated diodes is suppressed in low bias range with enhanced diode ideality factor and series resistance. However, in high bias range the treated diodes exhibit higher reverse leakage current and corresponding lower breakdown voltage. The X-ray photoelectron spectroscopy analysis reveals the growth of a thin GaOx layer on GaN surface during oxygen plasma treatment. Under sub-bandgap light illumination, the plasma-treated diodes show larger photovoltaic response compared with that of untreated diodes, suggesting that additional defect states at GaN surface are induced by the oxygen plasma treatment. 相似文献
10.
在研制AlGaN/GaN HEMT器件的基础上,采用ALD法制备了Al2O3 AlGaN/GaN MOSHEMT器件.通过X射线光电子能谱测试表明在AlGaN/GaN异质结材料上成功淀积了Al2O3薄膜.根据对HEMT和MOSHEMT器件肖特基电容、器件输出以及转移特性的测试进行分析发现:所制备的Al2O3薄膜与AlGaN外延层间界面态密度较小,因而MOSHEMT器件呈现出较
关键词:
2O3')" href="#">Al2O3
ALD
GaN
MOSHEMT 相似文献
11.
K. Prasad 《Applied Physics A: Materials Science & Processing》1992,54(6):493-496
Ruthenium was evaporated on n-GaAs to form Schottky contacts. Initial electrical measurements revealed a near ideal Schottky behaviour with low leakage currents. The Schottky diodes exhibit good stability upon thermal aging at elevated temperatures up to 300° C. However, the diode parameters rapidly deteriorate after aging at temperatures in excess of 400° C. The room temperature (300 K) median life of the diodes, based on a failure criterion of a tenfold increase in the diode saturation current, J
riv
s
, from reverse bias current-voltage (I–V) data, was of the order of 104 h. 相似文献
12.
Different temperature dependence of carrier transport properties between AlxGa1-xN/InyGa1-yN/GaN and AlxGa1-xN/GaN heterostructures
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The temperature dependence of carrier transport properties of AlxGa1-xN/InyGa1-yN/GaN and AlxGa1-xN/GaN heterostructures has been investigated.It is shown that the Hall mobility in Al0.25Ga0.75N/In0.03Ga0.97N/GaN heterostructures is higher than that in Al0.25Ga0.75N/GaN heterostructures at temperatures above 500 K,even the mobility in the former is much lower than that in the latter at 300 K.More importantly,the electron sheet density in Al0.25Ga0.75N/In0.03Ga0.97N/GaN heterostructures decreases slightly,whereas the electron sheet density in Al0.25Ga0.75N/GaN heterostructures gradually increases with increasing temperature above 500 K.It is believed that an electron depletion layer is formed due to the negative polarization charges at the InyGa1-yN/GaN heterointerface induced by the compressive strain in the InyGa1-yN channel,which e-ectively suppresses the parallel conductivity originating from the thermal excitation in the underlying GaN layer at high temperatures. 相似文献
13.
Wen-Chang Huang Shui-Hsiang Su Yu-Kuei Hsu Chih-Chia Wang Chen-Shiung Chang 《Superlattices and Microstructures》2006,40(4-6):644
A new Schottky diode, Al/p-GaSe, was presented in this study. It shows an effective barrier height of 0.96 eV with an ideality factor of 1.24 over five decades and a reverse leakage current density of 4.12×10−7 A/cm2 at −2 V after rapid thermal annealing at 400 C for 30 s. The generation–recombination effect of the Schottky diode was decreased as the annealing temperature was increased. The formation of Al1.33Se2 was observed by X-ray diffraction analysis after the diode was annealed at 400 C for 30 s. Owing to the grains’ growth, the surface morphology of the 400 C-annealed diode was rougher than that of the unannealed diode, which was observed both by the AFM and the SEM analysis. 相似文献
14.
We oxidized a Ni/Au metal bi-layer contact fabricated on HVPE Al0.18Ga0.82N from 373 K to 573 K in 100 K steps. In the range 1 kHz to 2 MHz, the Capacitance–Voltage–Frequency (C–V–f) measurements reveal a frequency dispersion of the capacitance and the presence of an anomalous peak at 0.4 V owing to the presence of interface states in the as deposited contact system. The dispersion was progressively removed by O2 anneals from temperatures as low as 373 K. These changes are accompanied by an improvement in the overall quality of the Schottky system: the ideality factor, n, improves from 2.09 to 1.26; the Schottky barrier height (SBH), determined by the Norde [1] method, increases from 0.72 eV to 1.54 eV. From the Nicollian and Goetzberger model [2], we calculated the energy distribution of the density of interface states, NSS. Around 1 eV above the Al0.18Ga0.82N valence band, NSS, decreases from 2.3×1012 eV−1 cm−2 for the un-annealed diodes to 1.3×1012 eV−1 cm−2 after the 573 K anneal. Our results suggest the formation of an insulating NiO leading to a MIS structure for the oxidized Au/Ni/Al0.18Ga0.82N contact. 相似文献
15.
Electronic and interface state distribution properties of Ag/p-Si Schottky diode have been investigated. The diode indicates non-ideal current-voltage behavior with an ideality factor greater than unity. The capacitance-voltage (C-V) characteristic is linear in reverse bias indicating rectification behavior and charge density within depletion layer is uniform. From I-V and C-V characteristics, junction parameters such as diode ideality factor and barrier height were found as 1.66 and ?B(I-V) = 0.84 eV (?B(C-V) = 0.90 eV), respectively. The interface state density Nss and relaxation time τ of the Schottky diode were determined by means of Schottky capacitance spectroscopy method. The results show the presence of thin interfacial layer between the metal and semiconductor. 相似文献
16.
The capacitance of an organic Schottky diode based on copper phthalocyanine (CuPc) is investigated. Based on the organic small-signal equivalent model established, we calculate the reverse capacitance CMetal Of the organic Schottky diode with different kinds of metal cathodes (Mg, Al, Au). It is found that the reverse capacitance of the organic Schottky diode shows behavior as CMg 〉 CAl 〉 CAu at the same frequency, and according to our analysis, the reverse Schottky junction capacitance Cj is expected to have little effect on the reverse capacitance of the organic Schottky diode, and the space-charge limited current capacitance Us is considered to dominate the reverse capacitance, which limits the improvement of frequency characteristics of organic Schottky diodes. 相似文献
17.
Woojin Jeon Sang Ho Rha Woongkyu Lee Cheol Hyun An Min Jung Chung Sang Hyun Kim Cheol Jin Cho Seong Keun Kim Cheol Seong Hwang 《固体物理学:研究快报》2015,9(7):410-413
The energy diagram of RuO2/Al‐doped TiO2/RuO2 structures was estimated from the capacitance–voltage and leakage current density–voltage curves. The Al‐doping profile in TiO2 film was varied by changing position of the atomic layer deposition cycle of Al2O3 during the atomic layer deposition of 9 nm‐thick TiO2 film. The interface between the TiO2 film and the RuO2 electrode containing Al‐doping layer showed a higher Schottky barrier by 0.1 eV compared with the opposite interface without the doping layer. The evolution of various leakage current profiles upon increasing the bias with opposite polarity could be well explained by the asymmetric Schottky barrier. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
18.
The current-voltage (I-V) characteristics of Al/Rhodamine-101/p-Si/Al contacts have been measured at temperatures ranging from 280 to 400 K at 20 K intervals. A barrier height (BH) value of 0.817 eV for the Al/Rh101/p-Si/Al contact was obtained at the room temperature that is significantly larger than the value of 0.58 eV of the conventional Al/p-Si Schottky diode. While the barrier height Φb0 decreases the ideality factors (n) become larger with lowering temperature. The high values of n depending on the sample temperature may be ascribed to decrease of the exponentially increase rate in current due to space-charge injection into Rh101 thin film at higher voltage. Therefore, at all temperatures, it has been seen that the I-V characteristics show three different regions, the ohmic behavior at low voltages, and the space charge limited current with an exponential distribution of traps at high voltages. 相似文献
19.
Thin film of non-polymeric organic compound pyronine-B has been fabricated on moderately doped (MD) n-InP substrate as an interfacial layer using spin coating technique for the electronic modification of Au/MD n-InP Schottky contact. The electrical characteristics have been determined at room temperature. The barrier height and the ideality factor values for Au/pyronine-B/MD n-InP Schottky diode have been obtained from the forward bias I-V characteristics at room temperature as 0.60 eV and 1.041; 0.571 and 1.253 eV after annealing at 100 and 250 °C, respectively. An increase in annealing temperature at the Au/n-InP Schottky junction is shown to increase the reverse bias leakage current by about one order of magnitude and decrease the Schottky barrier height by 0.027 eV. Furthermore, the barrier height values for the Au/pyronine-B/MD n-InP Schottky diode have also been obtained from the C-V characteristics at room temperature as 1.001 and 0.709 eV after annealing at 100 and 250 °C, respectively. Finally, it was seen that the diode parameters changed with increase in the annealing temperature. 相似文献
20.
针对极端环境下耐辐照半导体核探测器的研制需求,采用耐高温、耐辐照的4H碳化硅(4H-SiC)宽禁带材料制成肖特基二极管,研究了该探测器对241Am源粒子的电荷收集效率。从电容-电压曲线得出该二极管外延层净掺杂数密度为1.991015/cm3。从正向电流-电压曲线获得该二极管肖特基势垒高度为1.66 eV,理想因子为1.07,表明该探测器具备良好的热电子发射特性。在反向偏压高达700 V时,该二极管未击穿,其漏电流仅为21 nA,具有较高的击穿电压。在反向偏压为0~350 V范围内研究了该探测器对3.5 MeV 粒子电荷收集效率,在0 V时为48.7%,在150 V时为99.4%,表明该探测器具有良好的电荷收集特性。 相似文献