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51.
研究了在刻有图形的GaN"衬底”上用HVPE方法侧向外延生长(ELO)GaN的结构特性.在SiO2衬底上侧向外延生长GaN已经实现,并得到了平面的ELO GaN薄膜.采用扫描电子显微镜、透射电微镜和原子力显微镜技术研究了这种ELO GaN材料的结构和表面形貌.原子力显微镜图像表明:在ELO范围中的4μm2面积上不存在明显的阶状形貌.透射电子显微镜的观测表明在ELO范围内位错密度很低.在接合的界面上没观察到有空隙存在.但观测到晶格的弯曲高达3.3°,这被归因为由GaN层下的"籽层”和接合界面处的水平倾料和猝灭所产生的螺旋位错的积聚. 相似文献
52.
用薛定谔方程和泊松方程自洽计算的方法研究了Al0.75Ga0.25N/GaN对称双量子阱(DQWs)中子带间跃迁(ISBT)的波长和吸收系数对中间耦合势垒高度、中间耦合势垒宽度、势阱宽度和势垒掺杂浓度的依赖关系.研究发现,第一奇序子带S1ood与第二偶序子带S2even ISBT波长随着中间耦合势垒高度的降低而变短.当中间耦合势垒高度高于0.62 eV时,S1odd<
关键词:
自洽
xGa1-xN/GaN双量子阱')" href="#">AlxGa1-xN/GaN双量子阱
子带间跃迁 相似文献
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Different temperature dependence of carrier transport properties between AlxGa1-xN/InyGa1-yN/GaN and AlxGa1-xN/GaN heterostructures 下载免费PDF全文
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
55.
GaN epilayers were grown on sapphire substrates by metal-organic chemical vapour deposition. Metal-semiconductor-metal photoconductive detectors were fabricated using this material. The photocurrent properties of the detectors were measured and analysed. The spectrum response shows a high sensitivity in the wavelength region from 330 to 360nm, with a peak at 358nm and a sharp cutoff near 360nm. The maximum responsivities at 358nm were 700A/W (2V) and 7000A/W (30V). The relationship between responsivity and bias indicates that the responsivity increases linearly with bias until 30V. The influence of the spacing between two electrodes on the detector responsivity was also studied. 相似文献
56.
Influence of applied electric field on the absorption coefficient and subband distances in asymmetrical AlN/GaN coupled double quantum wells 下载免费PDF全文
The influence of applied electric fields on the absorption
coefficient and subband distances in asymmetrical AlN/GaN coupled
double quantum wells (CDQWs) has been investigated by solving
Schr?dinger and Poisson equations self-consistently. It is found
that the absorption coefficient of the intersubband transition
(ISBT) between the ground state and the third excited state (1odd-2even) can be equal to zero when the electric fields
are applied in asymmetrical AlN/GaN CDQWs, which is related to
applied electric fields induced symmetry recovery of these states.
Meanwhile, the energy distances between 1odd-2even
and 1even-2even subbands have different
relationships from each other with the increase of applied electric
fields due to the different polarization-induced potential drops
between the left and the right wells. The results indicate that an
electrical-optical modulator operated within the opto-communication
wavelength range can be realized in spite of the strong
polarization-induced electric fields in asymmetrical AlN/GaN CDQWs. 相似文献
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以氮化镓(GaN)、AlN(氮化铝)为代表的Ⅲ族氮化物宽禁带半导体是研制短波长光电子器件和高频、高功率电子器件的核心材料体系.由于缺少高质量、低成本的同质GaN和AlN衬底,氮化物半导体主要通过异质外延,特别是大失配异质外延来制备.由此导致的高缺陷密度、残余应力成为当前深紫外发光器件、功率电子器件等氮化物半导体器件发展的主要瓶颈,严重影响了材料和器件性能的提升.本文简要介绍了氮化物半导体金属有机化学气相沉积(MOCVD)大失配异质外延的发展历史,重点介绍了北京大学在蓝宝石衬底上AlN、高Al组分AlGaN的MOCVD外延生长和p型掺杂、Si衬底上GaN薄膜及其异质结构的外延生长和缺陷控制等方面的主要研究进展.最后对Ⅲ族氮化物宽禁带半导体MOCVD大失配异质外延的未来发展做了简要展望. 相似文献
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Leakage current reduction by thermal oxidation in Ni/Au Schottky contacts on lattice-matched In0.18Al0.82N/GaN heterostructures 下载免费PDF全文
By using temperature-dependent current–voltage, variable-frequency capacitance–voltage, and Hall measurements,the effects of the thermal oxidation on the electrical properties of Ni/Au Schottky contacts on lattice-matched In0.18Al0.82N/GaN heterostructures are investigated. Decrease of the reverse leakage current down to six orders of magnitude is observed after the thermal oxidation of the In0.18Al0.82N/GaN heterostructures at 700oC. It is confirmed that the reverse leakage current is dominated by the Frenkel–Poole emission, and the main origin of the leakage current is the emission of electrons from a trap state near the metal/semiconductor interface into a continuum of electronic states associated with the conductive dislocations in the InxAl1-xN barrier. It is believed that the thermal oxidation results in the formation of a thin oxide layer on the InxAl1-xN surface, which increases the electron emission barrier height. 相似文献