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71.
High-density and narrow size-distribution InAs quantum dots formed by a modified two-step growth 下载免费PDF全文
We develop a modified two-step method of growing high-density and
narrow size-distribution InAs/GaAs quantum dots (QDs) by molecular
beam epitaxy. In the first step, high-density small InAs QDs are
formed by optimizing the continuous deposition amount. In the second
step, deposition is carried out with a long growth interruption for
every 0.1 InAs monolayer. Atomic force microscope images show that
the high-density ($\sim $5.9$\times $10$^{10}$\,cm$^{ - 2})$ good
size-uniformity InAs QDs are achieved. The strong intensity and
narrow linewidth (27.7\,meV) of the photoluminescence spectrum show
that the QDs grown in this two-step method have a good optical
quality. 相似文献
72.
Atomic hydrogen induced step bunching and fabrication of quantum wire arrays on GaAs(311) A Substrate by molecular eam epitaxy 下载免费PDF全文
Atomic hydrogen assisted molecular beam epitaxy (MBE) is a novel type of epitaxial growth of nanostructures. The GaAs (311)A surface naturally forms one-dimensional step arrays by step bunching along the direction of 〈-233〉 and the space period is around 40nm. The step arrays extend over several μm without displacement. The InGaAs quantum wire arrays are grown on the step arrays as the basis. Our results may prompt further development of more uniform quantum wire and quantum dot arrays. 相似文献
73.
This paper studies the size dependence of biexciton binding energy
in single quantum dots (QDs) by using atomic force microscopy and
micro-photoluminescence measurements. It finds that the biexciton
binding energies in the QDs show ``binding' and ``antibinding'
properties which correspond to the large and small sizes of QDs,
respectively. The experimental results can be well interpreted by
the biexciton potential curve, calculated from the exciton molecular
model and the Heitler--London method. 相似文献
74.
Top-illuminated metamorphic InGaAs p-i-n photodetectors (PDs) with 50% cut-off wavelength of 1.75 μm at room temperature are fabricated on GaAs substrates. The PDs are grown by a solid-source molecular beam epitaxy system. The large lattice mismatch strain is accommodated by growth of a linearly graded buffer layer to create a high quality virtual InP substrate indium content in the metamorphic buffer layer linearly changes from 2% to 60%. The dark current densities are typically 5 × 10^-6 A/cm^2 at 0 V bias and 2.24 × 10^-4 A/cm^2 at a reverse bias of 5 V. At a wavelength of 1.55 μm, the PDs have an optical responsivity of 0.48 A/W, a linear photoresponse up to 5 mW optical power at -4 V bias. The measured -3 dB bandwidth of a 32 μm diameter device is 7 GHz. This work proves that InGaAs buffer layers grown by solid source MBE are promising candidates for GaAs-based long wavelength devices. 相似文献
75.
Growth and Magnetic Properties of Zincblende CrSb Epilayers on Relaxed and Strained (In, Ga)As Buffers 下载免费PDF全文
Zincblende CrSb (zb-CrSb) layers with room-temperature ferromagnetism have been grown on relaxed and strained (In,Ga)As buffer layers epitaxially prepared on (001) GaAs substrates by molecular-beam epitaxy. The structural characterizations of CrSb layers fabricated under the two cases are studied by using synchrotron grazing incidence x-ray diffraction (GID). The results of GID experiments indicate that no sign of second phase exists in all the zb-CrSb layers. Superconducting quantum interference device measurements demonstrate that the thickness of zb-CrSb layers grown on both relaxed and strained (In,Ga)As buffer layers can be increased to ~12 monolayers (~3.6nm), compared to ,~3 monolayers (~1 nm) on GaAs directly. 相似文献
76.
Enhancement of Photoluminescence Intensity of GaInNAs/GaAs Quantum Wells by Two-Step Rapid Thermal Annealing 下载免费PDF全文
We investigate the effect of rapid thermal annealing on InGaNAs/GaAs quantum wells. At optimized annealing temperatures and times, the greatest enhancement of the photoluminescence intensity is obtained by a special two-step annealing process. To identify the mechanism affecting the material quality during the rapid thermal annealing, differential temperature analysis is applied, and temperature- and power-dependent photoluminescence is carried out on the samples annealed under different conditions. Our experiment reveals that some composition redistribution or other related ordering processes may occur in the quantum-well layer during annealing. Annealing at a lower temperature for a long time primarily can remove defects and dislocations while annealing at a higher temperature for a short time primarily homogenizes the composition in the quantum wells. 相似文献
77.
Growth of high quality InSb thin films on GaAs substrates by molecular beam epitaxy method with AlInSb/GaSb as compound buffer layers 下载免费PDF全文
A series of In Sb thin films were grown on Ga As substrates by molecular beam epitaxy(MBE).Ga Sb/Al In Sb is used as a compound buffer layer to release the strain caused by the lattice mismatch between the substrate and the epitaxial layer,so as to reduce the system defects.At the same time,the influence of different interface structures of Al In Sb on the surface morphology of buffer layer is explored.The propagation mechanism of defects with the growth of buffer layer is compared and analyzed.The relationship between the quality of In Sb thin films and the structure of buffer layer is summarized.Finally,the growth of high quality In Sb thin films is realized. 相似文献
78.
采用光学方法确定InAs/GaAs单量子点在样品外延面上的位置坐标, 利用AlAs牺牲层把含有量子点的GaAs层剥离并放置在含有金纳米颗粒或平整金膜上, 研究量子点周围环境不同对量子点自发辐射寿命及发光提取效率的影响. 实验结果显示, 剥离前后量子点发光寿命的变化小于13%, 含有金纳米颗粒的量子点发光强度是剥离前的7倍, 含有金属薄膜的量子点发光强度是剥离前的2倍. 分析表明在金纳米颗粒膜上的量子点荧光强度的增加主要来自于金纳米颗粒对量子点荧光的散射效应, 从而提高量子点发光的提取效率. 相似文献
79.
Evolution of surface morphology and optical characteristics of 1.3-μm In0.5Ga0.5As/GaAs quantum dots (QDs) grown by molecular beam epitaxy (MBE) are investigated by atomic force microscopy (AFM) and photoluminescence (PL). After deposition of 16 monolayers (ML) of In0.5Ga0.5As, QDs are formed and elongated along the [120] direction when using sub-ML depositions, while large size InGaAs QDs with better uniformity are formed when using ML or super-ML depositions. It is also found that the larger size QDs show enhanced PL efficiency without optical nonlinearity, which is in contrast to the elongated QDs. 相似文献
80.
1.3μm GaInNAs量子阱RCE光探测器 总被引:6,自引:3,他引:3
采用配有dc-N plasma N源的分子束外延(MBE)技术在GaAs衬底上生长制作了工作波长为1,3μm的GaInNAs量子阱RCE探测器.采用传输矩阵法对器件结构进行优化.吸收区由三个GaInNAs量子阱构成,并用湿法刻蚀和聚酰亚胺对器件进行隔离.在零偏压下,器件最大的量子效率为12%,半峰值全宽(FWHM)为5.8nm,3dB带宽为30MHz,暗电流为2×10-11A.通过对MBE生长条件和器件结构的优化,将进一步提高该器件的性能. 相似文献