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1.
对Ga面p型GaN/Al0.35Ga0.65N/GaN应变异质结构中形成的二维空穴气(2DHG)进行了研究.首先基于半导体-绝缘体-半导体异质结构模型确定了应变异质中的临界厚度,然后自洽求解薛定谔方程和泊松方程,计算了当中间势垒层AlGaN处于完全应变状态和半应变状态两种条件下,顶层GaN及中间层AlGaN厚度的变化对2DHG分布的影响.计算结果表明,势垒层AlGaN和顶层GaN的应变状态和厚度对极化引起的2DHG面密度及分布有重要影响.在此基础上制备了p型GaN/Al0.35Ga0.65N/GaN应变量子阱结构肖特基器件,并通过器件的C-V测试证实了异质结处2DHG的存在.器件响应光谱的测试结果表明,由于p型GaN/Al0.35Ga0.65N/GaN量子阱中强烈的极化作用和Stark效应使得器件零偏压和反向偏压时的响应光谱都向短波方向移动了10 nm,在零偏压下器件在280 nm处的峰值响应为0.022 A/W,在反向偏压为1 V时,峰值响应达到0.19 A/W,已经接近理论值.
关键词:
AlGaN
二维空穴气
极化效应 相似文献
2.
正如人们所知, 可以通过电场或者设计非对称的半导体异质结构来调控体系的结构反演不对称性(SIA)和Rashba自旋劈裂. 本文研究了Al0.6Ga0.4N/GaN/Al0.3Ga0.7N/Al0.6Ga0.4N量子阱中第一子带的Rashba 系数和Rashba自旋劈裂随Al0.3Ga0.7N插入层(右阱)的厚度ws以及外加电场的变化关系, 其中GaN层(左阱)的厚度为40-ws Å. 发现随着ws的增加, 第一子带的Rashba系数和Rashba自旋劈裂首先增加, 然后在ws>20 Å 时它们迅速减小, 但是ws>30 Å时Rashba自旋劈裂减小得更快, 因为此时kf也迅速减小. 阱层对Rashba系数的贡献最大, 界面的贡献次之且随ws变化不是太明显, 垒层的贡献相对比较小. 然后, 我们假ws=20 Å, 发现外加电场可以很大程度上调制该体系的Rashba系数和Rashba自旋劈裂, 当外加电场的方向同极化电场方向相同(相反)时, 它们随着外加电场的增加而增加(减小). 当外加电场从-1.5×108 V·m-1到1.5×108 V· m-1变化时, Rashba系数随着外加电场的改变而近似线性变化, Rashba自旋劈裂先增加得很快, 然后近似线性增加, 最后缓慢增加. 研究结果表明可以通过改变GaN层和Al0.3Ga0.7N层的相对厚度以及外加电场来调节Al0.6Ga0.4N/GaN/Al0.3Ga0.7N/Al0.6Ga0.4N量子阱中的Rashba 系数和Rashba自旋劈裂, 这对于设计自旋电子学器件有些启示. 相似文献
3.
本文报道了作者提出的阶梯AlGaN外延层新型AlGaN/GaN HEMTs结构的实验结果. 实验利用感应耦合等离子体刻蚀(ICP)刻蚀栅边缘的AlGaN外延层, 形成阶梯的AlGaN 外延层结构, 获得浓度分区的沟道2DEG, 使得阶梯AlGaN外延层边缘出现新的电场峰, 有效降低栅边缘的高峰电场, 从而优化了AlGaN/GaN HEMTs器件的表面电场分布. 实验获得了阈值电压-1.5 V的新型AlGaN/GaN HEMTs器件. 经过测试, 同样面积的器件击穿电压从传统结构的67 V提高到新结构的106 V, 提高了58%左右; 脉冲测试下电流崩塌量也比传统结构减少了30%左右, 电流崩塌效应得到了一定的缓解. 相似文献
4.
Optimization of inductively coupled plasma deep etching of GaN and etching damage analysis 总被引:1,自引:0,他引:1
Inductively coupled plasma (ICP) etching of GaN with an etching depth up to 4 μm is systemically studied by varying ICP power, RF power and chamber pressure, respectively, which results in etch rates ranging from ∼370 nm/min to 900 nm/min. The surface morphology and damages of the etched surface are characterized by optical microscope, scanning electron microscope, atomic force microscopy, cathodoluminescence mapping and photoluminescence (PL) spectroscopy. Sub-micrometer-scale hexagonal pits and pillars originating from part of the structural defects within the original GaN layer are observed on the etched surface. The density of these surface features varies with etching conditions. Considerable reduction of PL band-edge emission from the etched GaN surface indicates that high-density non-radiative recombination centers are created by ICP etching. The density of these non-radiative recombination centers is found largely dependent on the degree of physical bombardments, which is a strong function of the RF power applied. Finally, a low-surface-damage etch recipe with high ICP power, low RF power, high chamber pressure is suggested. 相似文献
5.
6.
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
7.
Breakdown voltage analysis of Al0.25Ga0.75N/GaN high electron mobility transistors with partial silicon doping in the AlGaN layer
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In this paper,two-dimensional electron gas(2DEG) regions in AlGaN/GaN high electron mobility transistors(HEMTs) are realized by doping partial silicon into the AlGaN layer for the first time.A new electric field peak is introduced along the interface between the AlGaN and GaN buffer by the electric field modulation effect due to partial silicon positive charge.The high electric field near the gate for the complete silicon doping structure is effectively decreased,which makes the surface electric field uniform.The high electric field peak near the drain results from the potential difference between the surface and the depletion regions.Simulated breakdown curves that are the same as the test results are obtained for the first time by introducing an acceptor-like trap into the N-type GaN buffer.The proposed structure with partial silicon doping is better than the structure with complete silicon doping and conventional structures with the electric field plate near the drain.The breakdown voltage is improved from 296 V for the conventional structure to 400 V for the proposed one resulting from the uniform surface electric field. 相似文献
8.
An etching of oxynitride (SiON) films was conducted using an inductively coupled plasma. The experimental ranges for the radio frequency source power, the bias power, the pressure, and the C2F6 flow rates were 400-1000 W, 30-90 W, 6-12 mTorr, and 30-60 sccm, respectively. The etch characteristics examined include etch rate, profile angle, and microtrench. Particular emphasis was placed on the investigation of microtrench etch mechanisms. For this, both etch rate and profile angle variations were correlated to microtrench variation. In general, microtrench variation was complex depending on process parameters or experimental ranges given a certain parameter. Microtrench variation with the bias power was opposite to the profile angle variation. Little relationship between them was noticed for the source power variation. In contrast, microtrench variation was highly correlated to the profile angle variation for C2F6 flow rates. For the pressure variation, microtrench variation was reasonably explained by the distribution of polymer deposition. The empirical relationships identified can be utilized for microtrench control. 相似文献
9.
ICP power/RF power, operating pressure, and Cl2/BCl3 gas mixing ratio are altered to investigate the effect of input process parameters on the etch characteristics of GaN films. The etch selectivity of GaN over SiO2 and photoresist is studied. Although higher ICP/RF power can obtain higher GaN/photoresist etch selectivity, it can result in faceting of sidewall and weird sidewall profile due to photoresist mask erosion. Etch rates of GaN and SiO2 decrease with the increase of operating pressure, and etch selectivity of GaN over SiO2 increases with the increasing operating pressure at fixed ICP/RF power and mixture component. The highest etch selectivity of GaN over SiO2 is 7.92, and an almost vertical etch profile having an etch rate of GaN close to 845.3 nm/min can be achieved. The surface morphology and root-mean-square roughness of the etched GaN under different etching conditions are evaluated by atomic force microscopy. The plasma-induced damage of GaN is analyzed using photoluminescence (PL) measurements. The optimized etching process, used for mesa formation during the LED fabrication, is presented. The periodic pattern can be transferred into GaN using a combination of Cl2/BCl3 plasma chemistry and hard mask SiO2. Patterning of the sapphire substrate for fabricating LED with improved extraction efficiency is also possible using the same plasma chemistry. 相似文献
10.
�� �ƣ�������� ��������Ƽ 《核聚变与等离子体物理》2018,38(1):105-109
通过轴向移动朗缪尔探针,考察了外置电磁铁提供的横向磁场对射频感应耦合等离子体(ICP)延轴向扩散过程中的电子温度、离子密度的影响。实验数据表明,与无磁场条件下的结果相比,横向磁场的加入使得扩散区内的电子温度沿轴向迅速下降,研究了横向磁场对电子的过滤作用。 相似文献
11.
Both electrical and optical activation studies of Si-implanted Al0.18Ga0.82N have been made as a function of anneal time and anneal temperature to obtain maximum possible electrical activation efficiency. Silicon ions were implanted at 200 keV with doses of 5×1014 and 1×1015 cm−2, and the samples were annealed from 1100 to 1250 °C for 5-25 min with a 500 Å thick AlN cap in a nitrogen environment. The electrical activation efficiency and Hall mobility increase with anneal time and anneal temperature. Nearly 100 and 95% electrical activation efficiencies were obtained for Si-implanted Al0.18Ga0.82N with doses of 5×1014 and 1×1015 cm−2 and annealing at 1250 and 1200 °C for 25 min, respectively. The photoluminescence measurements show an excellent implantation damage recovery after annealing at these optimum anneal conditions, showing a strong near band emission. These optical results correlate well with the electrical results. 相似文献
12.
Strain relaxation and optical properties of etched In0.19Ga0.81N nanorod arrays on the GaN template
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InGaN/GaN epilayers,which are grown on sapphire substrates by the metal-organic chemical-vapour deposition(MOCVD) method,are formed into nanorod arrays using inductively coupled plasma etching via self-assembled Ni nanomasks.The formation of nanorod arrays eliminates the tilt of the InGaN(0002) crystallographic plane with respect to its GaN bulk layer.Photoluminescence results show an apparent S-shaped dependence on temperature.The light extraction efficiency and intensity of photoluminescence emission at low temperature of less than 30 K for the nanorod arrays are enhanced by the large surface area,which increases the quenching effect because of the high density of surface states for the temperature above 30 K.Additionally,a red-shift for the InGaN/GaN nanorod arrays is observed due to the strain relaxation,which is confirmed by reciprocal space mapping measurements. 相似文献
13.
By solving the Schrödinger and Poisson equations self-consistently, changes of the Rashba spin splitting for the Al0.3Ga0.7N/GaN heterostructure under uniaxial strain are calculated, and electrons are found to take up the first two subbands. The additional polarization induced by the uniaxial strain leads to a great enhancement of the built-in electric field and the 2DEG concentration. The Rashba spin splitting almost increases linearly with the uniaxial strain, and its amplitude increases by 36% with a strain of 4×10−3. The effect of electrons occupying more than one subband on the Rashba spin splitting is discussed. Results show the internal electric field caused by the polarization is crucial for the considerable Rashba spin splitting in the Al0.3Ga0.7N/GaN heterostructure and the magnitude of the Rashba spin splitting can be greatly modulated by the uniaxial strain, which would benefit further research and application of spintronics. 相似文献
14.
为了优化AlGaN/GaN HEMTs器件表面电场,提高击穿电压,本文首次提出了一种新型阶梯AlGaN/GaN HEMTs结构.新结构利用AlGaN/GaN异质结形成的2DEG浓度随外延AlGaN层厚度降低而减小的规律,通过减薄靠近栅边缘外延的AlGaN层,使沟道2DEG浓度分区,形成栅边缘低浓度2DEG区,低的2DEG使阶梯AlGaN交界出现新的电场峰,新电场峰的出现有效降低了栅边缘的高峰电场,优化了AlGaN/GaN HEMTs器件的表面电场分布,使器件击穿电压从传统结构的446 V,提高到新结构的640 V.为了获得与实际测试结果一致的击穿曲线,本文在GaN缓冲层中设定了一定浓度的受主型缺陷,通过仿真分析验证了国际上外延GaN缓冲层时掺入受主型离子的原因,并通过仿真分析获得了与实际测试结果一致的击穿曲线. 相似文献
15.
A novel 6SrO·6BaO·7Al2O3 (S6B6A7) thin film has been deposited onto soda lime float glass via sol-gel dip coating technique. The optical and electrical properties of S6B6A7 films annealed in air and H2 atmosphere have been investigated. The structural and compositional properties of the S6B6A7 thin films have been investigated using Fourier transferred infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The S6B6A7 films prepared using 5 (wt.%) sol and annealed at 450 °C in air and H2 atmosphere exhibit an average transmittance of over ∼91% in wide visible range. The electrical properties of the S6B6A7 films affect film thickness as revealed by sheet resistance measurements. The sheet resistance of the 150 nm S6B6A7 films was 67.85 and 6.06 kilo ohms per square for air and H2 annealed, respectively. 相似文献
16.
For further prolonging the serve life of silicone rubber (SIR) for outdoor insulation and increasing its resistance of pollution flashover, surface modifications of SIR were carried out via CF4 capacitively coupled plasma at radio frequency (RF) power of 60, 100 and 200 W for a treatment time up to 20 min under CF4 flow rate of 20 sccm. Static contact angle measurement was employed to estimate the change of hydrophobicity of the modified SIR. The variation of the surface functional groups of the modified SIR was observed by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrum and X-ray photoelectron spectroscopy (XPS). The surface topography was observed by atom force microscopy (AFM). The results indicate that the static contact angle of SIR surface is improved from 100.7° to 150.2° via the CF4 plasma modification, and the super-hydrophobic surface of modified SIR, which corresponds to a static contact angle of 150.2°, appears at RF power of 200 W for a 5-min treatment time. According to the results, it is suggested that the formation of super-hydrophobic surface is ascribed to the co-action of the increase of roughness created by the ablation reaction of CF4 plasma and the formation of [SiFx(CH3)2−xO]n (x = 1, 2) structure produced by the direct attachment of F atoms to Si. 相似文献
17.
用高分辨X射线衍射仪(HRXRD)研究了表面钝化前后Al0.22Ga0.78N/ GaN异质结势垒层应变的高温特性,温度变化范围从室温到813K.结果表明,对未钝化的异质 结,当测试温度高于523K时,Al0.22Ga0.78N势垒层开始出现应变 弛豫;钝化后,在Al0.22Ga0.78N势垒层中会产生一个附加的平面 拉伸应变,并随着温度的增加,势垒层中的平面拉伸应变会呈现出一个初始的增加,接着应 变将减小,对100nm厚的Al0.22Ga0.78N势垒层,应变只是轻微地减 小,但对于50nm厚的Al0.22Ga0.78N势垒层,则出现了严重的应变 弛豫现象.
关键词:
0.22Ga0.78N/GaN异质结')" href="#">Al0.22Ga0.78N/GaN异质结
应变
3 N4钝化')" href="#">Si3 N4钝化
高温XRD 相似文献
18.
Kanchan Talele 《Optik》2011,122(7):626-630
Analysis of carrier transport properties in GaN based multiple quantum well nanostructure has been carried out with an applied bias. Effect of an applied bias and aluminium mole composition in the barrier on the scattering rate, capture time and escape rate has been investigated. The scattering rate was found to be decreased with an increase of applied bias voltage and aluminium mole composition. Capture time shows oscillatory nature with variations in mole composition of aluminium under biasing conditions. The escape rate was found to be increasing from 0.01 ps−1 to 0.69 ps−1 with applied bias voltage. 相似文献
19.
Cuimei Wang Guoxin Hu Junxi Wang Jianping Li Zhanguo Wang 《Applied Surface Science》2006,253(2):762-765
Unintentionally doped high-Al-content Al0.45Ga0.55N/GaN high electron mobility transistor (HEMT) structures with and without AlN interfacial layer were grown by metal-organic chemical vapor deposition (MOCVD) on two-inch sapphire substrates. The effects of AlN interfacial layer on the electrical properties were investigated. At 300 K, high two-dimensional electron gas (2DEG) density of 1.66 × 1013 cm−2 and high electron mobility of 1346 cm2 V−1 s−1 were obtained for the high Al content HEMT structure with a 1 nm AlN interfacial layer, consistent with the low average sheet resistance of 287 Ω/sq. The comparison of HEMT wafers with and without AlN interfacial layer shows that high Al content AlGaN/AlN/GaN heterostructures are potential in improving the electrical properties of HEMT structures and the device performances. 相似文献
20.
《Current Applied Physics》2020,20(1):196-204
CO2 dissociation and CH4 dry reforming, by high power inductively coupled plasma (ICP) torch at atmospheric pressure, have been studied. At a frequency of 400 kHz and power of 30 kW, the ICP torch source dissociates CO2 gas directly, causing CH4 dry reforming. The resulting products are composed of syngas, C2H6, C2H4, and C2H2. The results show conversion efficiencies (CE) for both CO2 and CH4 of 95%. At an input power of 22 kW, a CO2 flow rate of 30 SLM, and a CH4 flow rate of 36 SLM, the energy conversion efficiency (ECE) is 57%. As input CH4 flow rate increases, the selectivity of CO and H2 decreases and that of C2 hydrocarbons increases. In this condition, ECE increases. As a result, the high CE of CO2 and CH4, the large amount of products, and the high selectivity of C2 hydrocarbons can be seen as important factors for achieving higher energy conversion efficiency in the CH4 dry reforming process. The associated chemical reactions are simulated using CHEMKIN-PRO tool, and the results illustrate the tendency of CE to vary with variations in selected parameters, and syngas and C2 hydrocarbons production trends achieved in the simulation agree with experimental results. 相似文献