共查询到19条相似文献,搜索用时 109 毫秒
1.
2.
MBE[(AI_xGa_(1-x)As)_l(GaAs)_m_n/GaAs(001)超晶格结构参数的X射线双晶衍射测量研究 总被引:6,自引:0,他引:6
本文根据超晶格结构的台阶模型,利用X射线衍射的运动学模型,导出了超晶格的X射线衍射峰的相对光强比.利用X射线双晶衍射方法测定了MBE[(Al_xGa_(1-x)As)_1(GaAs)_m]./GaAs(001)一维超晶格的衍射迴摆曲线,除超晶格的主衍射峰外,还观察到一级和二级卫星峰.由这些衍射峰之间的角距离和相对光强比,计算出了超晶格的结构参数,其中包括周期D、垒宽L_B、量子阱宽度L_Z和Al含量x值. 相似文献
3.
本文根据超晶格结构的台阶模型,利用X射线衍射的运动学模型,导出了超晶格的X射线衍射峰的相对光强比.利用X射线双晶衍射方法测定了MBE[(Al_xGa_(1-x)As)_1(GaAs)_m]./GaAs(001)一维超晶格的衍射迴摆曲线,除超晶格的主衍射峰外,还观察到一级和二级卫星峰.由这些衍射峰之间的角距离和相对光强比,计算出了超晶格的结构参数,其中包括周期D、垒宽L_B、量子阱宽度L_Z和Al含量x值. 相似文献
4.
InAs/GaSb II类超晶格探测器是近年来国际上发展迅速的红外探测器,其优越性表现在高量子效率和高工作温度,以及良好的均匀性和较低的暗电流密度,因而受到广泛关注。报道了InAs/GaSb超晶格中波材料的分子束外延生长和器件性能。通过优化分子束外延生长工艺,包括生长温度和快门顺序等,获得了具原子级表面平整的中波InAs/GaSb超晶格材料,X射线衍射零级峰的双晶半峰宽为28.8,晶格失配a/a=1.510-4。研制的p?鄄i?鄄n单元探测器在77 K温度下电流响应率达到0.48 A/W,黑体探测率为4.541010 cmHz1/2W,峰值探测率达到1.751011 cmHz1/2W。 相似文献
5.
插入n-AlGaN/GaN超晶格改善GaN基LED的droop效应 总被引:1,自引:1,他引:0
在GaN基LED的n-GaN和InGaN/GaN发光区之间插入n-AlGaN/GaN超晶格来改善其droop效应。注入电流低于100mA时,插入n-AlGaN/GaN超晶格的LED的流明效率低于没有插入层的LED。注入电流高于100mA时,插入n-AlGaN/GaN超晶格的LED的流明效率高于没有插入层的LED。插入n-AlGaN/GaN超晶格后,GaN基LED在-5V的反向电压下,漏电由2.568029μA减少到0.070543μA。人体模式下,插入n-AlGaN/GaN超晶格的LED在2000V的静电电压下的通过率从60%提高到了90%。LED droop效应的改善是因为n-AlGaN/GaN超晶格过滤了穿透位错并改善了电流扩展能力。 相似文献
6.
7.
MBE GaAs/AlAs一维超晶格结构参数的X射线双晶衍射测量 总被引:7,自引:1,他引:6
用X射线双晶衍射法测定了MBE GaAs/AlAs一维超晶格的衍射迥摆曲线.除超晶格的主衍射峰外,还观察到一级和二级卫星峰.由这些衍射峰之间的角距离△θ,计算出超晶格的周期宽度D,进而确定AlAs层厚L_B和GaAs层厚L2. 相似文献
8.
本文提出热激活辐射过程和Berthelot-型的非辐射复合过程互相竞争的简单模型解释无序半导体超晶格的光荧光随温度变化行为,预言了当温度升高荧光衰变时间在某一温度附近快速下降;获得了高温时较大无序度的半导体超晶格比较小无序度的半导体超晶格荧光强,在低温时情况相反;且荧光峰随温度变化存在一个最大值。理论结果与实验观察到的无序半导体超晶格荧光行为一致。 相似文献
9.
在18~300K 度范围内测量了 GaAs/AlGaAs 超晶格和 Ge_xSi_(1-x)/Si 应变层超晶格在不同温度下的光伏谱。在200K 以下,在 GaAs/AlGaAs 超晶格中观测到6个子带间光跃迁激子峰;在100K 以下,GaAs/AlGaAs 的光伏谱反映了超晶格台阶状态密度分布。在 Ge_xSi_1-x/Si 应变层超晶格中,观测到子带和连续带间的光跃迁。并对两类超晶格的光伏特性进行了比较分析。 相似文献
10.
11.
Mao-Chieh Hsu Chun-Chi Chen Chieh-Hsiung Kuan Shiang-Yu Wang 《Quantum Electronics, IEEE Journal of》2003,39(11):1476-1480
Intersubband and free-carrier associated photoresponse in a GaAs-AlGaAs superlattice infrared photodetector is investigated. Under reverse bias, the photodetector is similar to an internal photoemission photodetector and significant photoresponse due to free-carrier absorption at the collector contact is found. In particular, in our photodetector, intersubband transitions at the superlattice layer also play an important role at low reverse biases and produce a photocurrent with an opposite direction to that of the free-carrier associated photocurrent. Since the total photocurrent consists of two components with opposite signs, photocurrent reversal occurs in the response spectrum. At high reverse bias, the intersubband-associated photoresponse is fully suppressed by the blocking barrier and the overall photoresponse is mainly due to the photoemission via free-carrier absorption at the collector contact. The intersubband and free-carrier associated photocurrent components under reverse bias can be resolved from the measured polarization dependence of the spectral response. The analysis of the measured free-carrier associated photocurrent agrees with previous studies on free-carrier absorption. A possible application with our detector to determine the wavelength of a monochromatic light is also demonstrated. 相似文献
12.
Jwo S.-C. Wu M.-T. Chen J.-K. Hong J.-W. Chang C.-Y. 《Electron Devices, IEEE Transactions on》1988,35(8):1279-1283
An a-Si/SiC:H superlattice avalanche photodiode (SAPD) has been successfully fabricated on an ITO/glass substrate by plasma-enhanced chemical vapor deposition. The room-temperature electron and hole impact ionization rates, α and β, have been determined for the a-Si/SiC:H superlattice structure by photocurrent multiplication measurements. The ratio α/β is 6.5 at a maximum electric field of 2.08×105 V/cm. Avalanche multiplications in the superlattice layer yields an optical gain of 184 at a reverse bias V R=20 V and an incident light power P in=5 μW. An LED-SAPD photocouple exhibited a switching time of 4.5 μs at a load resistance R -1.8 kΩ 相似文献
13.
14.
The characterisation of an 8 μm infrared photovoltaic detector based on InAs/GaSb superlattices is carried out at 77 K for the first time. The built-in field is established by the Fermi level difference between the superlattice surface and the InAs buffer layer. The photocurrent is from photoexcited carriers traversing through the superlattice conduction miniband. A current responsivity of 0.07 A/W has been obtained, implying that one out of 10 photoexcited electrons has been collected 相似文献
15.
Temperature-dependence and excitation-intensity-dependence of photoluminescence spectra for both disordered and ordered Ga0.52 In0.48P are measured.The disordered sample is charactierized by its single pcak photoluminescence spectrum which is excitation-intensity.independent and has different activation energy at different temperature region.The ordered sample shows double peaks,the intensity of the high-energy peak has an anomalous increase firstly and quenches afterwards.The relative henomena are reasonably explained in terms of lattice ordering and orientation superlattice model. 相似文献
16.
17.
基于碰撞离化理论研究了异质材料超晶格结构对载流子离化率的作用,设计得到In0.53Ga0.47As/In0.52Al0.48As超晶格结构的雪崩光电二极管。通过分析不同结构参数对器件性能的影响,得到了低隧道电流、高倍增因子的超晶格结构雪崩层,根据电场分布方程模拟了器件二维电场分布对电荷层厚度及掺杂的依赖关系,并优化了吸收层的结构参数。对优化得到的器件结构进行仿真并实际制作了探测器件,进行光电特性测试,与同结构普通雪崩光电二极管相比,超晶格雪崩光电二极管具有更强的光电流响应,在12.5~20 V的雪崩倍增区,超晶格雪崩光电二极管在具备高倍增因子的同时具有较低的暗电流,提高了器件的信噪比。 相似文献
18.
19.
基于激子基,采用密度矩阵理论研究了太赫兹场作用下半导体超晶格的子带间动力学过程及光吸收谱。在太赫兹场的驱动下,激子作布洛赫振荡。子带间极化的缓慢变化依赖于太赫兹频率,随着太赫兹频率的增加,子带间极化向下振荡,极化强度降低。以 和 两种超晶格为例进行研究,它们的光吸收谱出现了卫星峰结构,这是由于太赫兹场与万尼尔斯塔克阶梯激子作用的非线性效应产生的。但是就 与 超晶格相比而言,我们研究发现,n<0的激子态与n=0的激子态耦合作用较强使得光吸收谱吻合性较好,n=0时的激子态吸收光谱出现红移,n>0的激子态光吸收谱中出现的边带效应不是很明显。 相似文献