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AlxGa1-xAs/GaAs合金型异质结价带偏移的研究中,采用以平均键能为参考能级的ΔEv理论计算方法,得到ΔEv(x)=0.531x+0.001x2的理论计算结果.该计算结果与目前的一些实验结果符合较好. 相似文献
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本文采用三角阱近似,考虑了GaAs/AlxGa1-xAs二维电子气(2DEG)异质结中七种主要的散射机制,计算了2DEG电子迁移主经与隔离层厚度(d)和Al组分(x)的关系,对GaAs/AlxGa1-xAs异质结的结构参数进行了优化分析。就作者所知,本文首次计算了2DEG电子迁移率与Al组分x的关系,得到了与实验规律一致的结果。 相似文献
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在71—163K的不同稳定温度下,对GaAs-Al0.3Ga0.7As调制掺杂异质结构界面的光激发过剩电子的浓度,作了10-5-103秒时间范围的瞬变测量.一个包含了热声子辅助隧穿,Si掺杂的AlxGa1-xAs层DX中心俘获势垒分布和隧穿后电子的能量弛豫过程的理论计算可以定量地解释实验结果. 相似文献
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AlxGa1-xAs/GaAs合金型异质结价带偏移的研究中,采用以平均键能为参考能级的ΔEV理论计算方法,得到ΔEv(x)=0.531x+0.001x^2的理论计算结果。该计算结果与目前的一些实验结果符合较好。 相似文献
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GaAs/AlxGa1—xAs和AlxGa1—xAs/AlAs超晶格的喇曼散射对比研究 总被引:1,自引:0,他引:1
报道不同层厚的AlAs/AlxGa1-xAs及GaAs/AlxGa1-xAs短周期超晶格的纵光学声子模的室温喇曼散射测量结果.在非共振条件下,观察到AlAs/AlxGa1-xAs中限制在AlxGa1-xAs混晶层中的类GaAsLO限制模和限制在AlAs层中的AlAsLO限制模,还观察到GaAs/AlxGa1-xAs中限制在AlxGa1-xAs混晶层中的类AlAsLO限制模和限制在GaAs层中的GaAsLO限制模.在近共振条件下,还观察到了AlAs/AlxGa1-xAs中AlAs的界面模.根据线性链模型,把测量的LO限制模的频率按照q=mn+12πα0展开,给出了AlxGa1-xAs混晶的类AlAs支和类GaAs支光学声子色散曲线. 相似文献
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本文较系统和全面地总结了GaAs和AlxGa1-xAs材料的物理参数模型,包括介电常数、能带参数、载流子迁移率以及复合机制和寿命等,给出了易于应用的数学公式,其中AlxGa1-xAs重掺杂能带窄变公式为本文首次推导。这些物理参数模型对于AlxGa1-xAs/GaAs异质结器件的研究有着十分重要的意义。 相似文献
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应用深能级瞬态谱(DLTS)技术研究分子束外延(MBE)和二次液相外延(LPE)生长的InGaAs/GaAs应变层量子季阱激光器深中心行为.在MBE激光器的n-AlxGa1-xAs组分缓变层和限制层里,除众所周知的DX中心外,还观察到有较大俘获截面的深(空穴、电子)陷阱及其相互转化.这些陷阱可能分布在x从0到0.40和x—0.40的n-AlxGa1-xAs层里x值不连续的界面附近.而在LPE激光器的n-AlxGa1-xAs组分缓变层和限制层里,DX中心浓度明显减少,且深(空穴、电子)陷阱消失 相似文献
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W. Z. Shen W. G. Tang S. C. Shen S. M. Wang T. Anderson 《Journal of Infrared, Millimeter and Terahertz Waves》1994,15(10):1643-1650
The influence of the GaAs cap layer thickness on the luminescence properties in strained In0.20Ga0.80As/GaAs single quantum well (SQW) structures has been investigated using temperature-dependent photoluminescence (PL) spectroscopy. The luminescence peak is shifted to lower energy as the GaAs cap layer thickness decreases, which demonstrates the effect of the GaAs cap layer thickness on the strain of InGaAs/GaAs single quantum wells (SQW). We find the PL quenching mechanism is the thermal activation of electron hole pairs from the wells into the GaAs cap layer for the samples with thicker GaAs cap layer, while in sample with thinner GaAs cap layer exciton trapping on misfit dislocations is dominated. 相似文献
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Saitoh M. Kamimuta Y. Saito T. Sekine K. Kobayashi T. Aoyama T. Koyama M. Nishiyama A. 《Electron Devices, IEEE Transactions on》2007,54(7):1689-1695
We propose sub-1-A-resolution analysis of gate surface layer In scaled-Tinv (capacitance equivalent thickness at substrate inversion) gate stacks by differentiating their C-V curves. By introducing the universal derivative-of-capacitance curve, gate stacks with different equivalent oxide thickness of gate insulator and substrate-impurity concentration JVSub can be analyzed in one and the same plot. By applying this analysis technique to p+ poly-Si/HfSiON stack, it is found that gate depletion increases due to both lower poly impurity concentration Npoly and high pinning charge density Nox inside the dielectric. Ultrathin SiN cap insertion onto HfSiON recovers the degradation in Npoly and Nox leading to suppression of gate depletion and flatband voltage shift. 相似文献
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S. Bürkner M. Maier E. C. Larkins W. Rothemund E. P. O’reilly J. D. Ralston 《Journal of Electronic Materials》1995,24(7):805-812
The dependence of the impurity-free interdiffusion process on the properties of the dielectric cap layer has been studied,
for both unstrained GaAs/AlxGa1−xAs and pseudomorphic Iny Ga1−yAs/GaAs MQW structures grown by molecular beam epitaxy. The influence of the cap layer thickness, composition, and deposition
technique on the degree of interdiffusion were all systematically investigated. Electron-beam evaporated SiO2 films of varying thickness, chemical-vapor-deposited SiOxNy films of varying composition, and spin-on SiO2 films were used as cap layers during rapid thermal annealing (850-950°C). Photoluminescence at 10K has been employed to determine
the interdiffusioninduced bandgap shifts and to calculate the corresponding Al-Ga and In-Ga interdiffusion coefficients. The
latter were found to increase with the cap layer thickness (e-beam SiO2) up to a limit determined by saturation of the outdiffused Ga concentration in the SiO2 caps. A maximum concentration of [Ga] = 4–7 ×1019 cm−3 in the SiO2 caps was determined using secondary ion mass spectroscopy profiling. Larger band-edge shifts are also obtained when the oxygen
content of SiOxNy cap layers is increased, although the differences are not sufficiently large for a laterally selective interdiffusion process
based on variations in cap layer composition alone. Much larger differences are obtained by using different deposition techniques
for the cap layers, indicating that the porosity of the cap layer is a much more important parameter than the film composition
for the realization of a laterally selective interdiffusion process. For the calculated In0.2Ga0.8As/GaAs interdiffusion coefficients, activation energies EA and prefactors Do were estimated to ranging from 3.04 to 4.74 eV and 5 × Kh−3 to 2 × 105 cm2/s, respectively, dependent on the cap layer deposition technique and the depth of the MQW from the sample surface. 相似文献
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Dae Kon Oh Kyung Soo Suh Heungro Choo Hong Man Kim Kwang Eui Pyun Hyoung-Moo Park Sahn Nahm 《Journal of Electronic Materials》1996,25(3):485-489
(InAs)m(GaAs)m (1 ≤ m ≤ 12) short period superlattices (SPSs) have been grown on semi-insulated InP substrates with a 200 nm InP cap layer using low pressure metalorganic chemical vapor deposition (MOCVD). According to double crystal x-ray diffraction and transmission electron microscopy results, the critical layer thickness of (InAs)m(GaAs)m SPS was observed to be ~30Å (m = 5). For the SPS below the critical layer thickness, mirror-like surface morphology was found without defects, and strong intensity Fourier transformed photoluminescence (FT-PL) spectra were also obtained at room temperature. The SPS with m = 4 showed a drastic improvement in photoluminescence intensity of order of two compared to an InGaAs ternary layer. However, the SPS with a large value of m (m ≥ 6), rough surface was observed with defects, with broad and weak FT-PL spectra. The surface morphology of SPS was greatly affected by the substrate orientation. The SPS with m = 5 was grown on two degree tilted substrate from (100) direction and showed poor surface morphology as compared to the one grown on (100) exact substrate Moreover, the SPS grown on a (111)B substrate showed a rough triangular pattern with Nomarski optical microscopy. In-situ thermal annealed SPS with m = 4 showed a 18 meV increase in PL peak energy compared to the as-grown sample due to phase separation resulting from thermal interdiffusion. 相似文献
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通过化学气相沉积法,采用不同生长工艺在4°偏角4H-SiC衬底上制备p型4H-SiC同质外延片。提出了p型4H-SiC同质外延中有效层厚度的概念,研究发现导致外延有效层厚度减少的直接原因是自掺杂效应的存在。采用傅里叶红外光谱仪(FT-IR)、汞探针电容电压(Hg-CV)和表面缺陷测试仪对p型4H-SiC同质外延片进行表征,讨论了不同工艺对外延有效层厚度的影响。结果表明,采用隔离法和阻挡层法均能提高外延有效层厚度,且掺杂浓度随距表面深度变化斜率值由1.323减小到0.073。然而,阻挡层法斜率值能进一步优化至0.050,是由于有效抑制了外延中固相和气相自掺杂。对比于优化前工艺,采用阻挡层法制备的p型4H-SiC同质外延片厚度不均匀性和表面总缺陷数量处于同一水平,掺杂浓度不均匀性由2.95%改善到2.67%。综上,采用阻挡层法能够制备出高有效层厚度、高一致性和高质量的p型4H-SiC同质外延片。 相似文献
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低温下,在蓝宝石图形衬底上使用金属有机化学气相沉积(MOCVD)生长低温GaN(LT-GaN)缓冲层,并对其表面形貌进行了细致的观察,发现了不同于已报道的GaN选择性成核生长现象。基于不同厚度的低温GaN缓冲层生长了n型GaN(n-GaN),发现过厚或者过薄的缓冲层都会对n-GaN晶体质量产生负面影响,并结合初始成核阶段进行了原因分析。制备了基于不同厚度的n-GaN的发光二极管(LED)样品,分析了GaN晶体质量对LED输出功率的影响。同时发现,晶体质量较差的时候,光提取效率可能主导着对LED器件性能的影响。 相似文献
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A. V. Bobyl A. A. Gutkin P. N. Brunkov I. A. Zamoryanskaya M. A. Yagovkina Yu. G. Musikhin D. A. Sakseev S. G. Konnikov N. A. Maleev V. M. Ustinov P. S. Kopjev V. T. Punin R. I. Ilkaev Zh. I. Alferov 《Semiconductors》2006,40(6):687-690
The influence of gamma radiation on multilayer AlGaAs/InGaAs/GaAs transistor heterostructures has been studied by means of X-ray diffraction analysis and transmission electron microscopy. It was found that irradiation with doses exceeding ~3 × 107 rad leads to destruction of the GaAs layer on the surface of these structures. An irradiation dose of 108 rad significantly deteriorates the surface planarity, with the surface roughness reaching values of several nanometers. In addition, dislocations are formed in the cap layer of the structure. Such a behavior of the cap layer may be due to the existence of an oxide layer on its free surface and to the possible chemical reactions, induced by gamma radiation, between atoms of the cap layer and free radicals formed in the oxide and in the ambient atmosphere. No noticeable changes in the structure and composition of the thin InGaAs channel layer occur at doses lower than 108 rad. 相似文献
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S.J. Chang L.W. Wu Y.K. Su Y.P. Hsu W.C. Lai J.M. Tsai J.K. Sheu C.T. Lee 《Photonics Technology Letters, IEEE》2004,16(6):1447-1449
GaN-based light-emitting diodes (LEDs) with various p-cap layers were prepared. It was found that surface morphologies of the LEDs with 800/spl deg/C grown cap layers were rough due to the low lateral growth rate of GaN. It was also found that 20-mA forward voltage of the LED with 800/spl deg/C grown p-AlInGaN-GaN double-cap layer was only 3.05 V. Furthermore, it was found that we could achieve a high output power and a long lifetime by using the 800/spl deg/C grown p-AlInGaN-GaN double-cap layer. 相似文献
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Yu C. L. Chuang R. W. Chang S. J. Chang P. C. Lee K. H. Lin J. C. 《Photonics Technology Letters, IEEE》2007,19(11):846-848
InGaN-GaN multiple-quantum-well metal-semiconductor-metal photodiodes (PDs) with in situ grown 40-nm-thick unactivated semi-insulating Mg-doped GaN cap layer were successfully fabricated. The dark leakage current of this PD was comparably much smaller than that of conventional PD without the semi-insulating layer, because of a thicker and higher potential barrier of semi-insulating cap layer, and also a smaller number of surface states involved. For the PDs with the semi-insulating Mg-doped GaN cap layers, the responsivity at 380nm was 0.372A/W when biasing at 5 V. In short, incorporating a semi-insulating Mg-doped GaN cap layer into the PDs beneficially leads to the suppression of dark current and a corresponding improvement in the ultraviolet-to-visible rejection ratio 相似文献
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