Proposal and Estimation of High Polarization and High Quantum Efficiency Semiconductor Photocathode

高偏振高量子效率半导体光电阴极的提议和评估

基本信息

批准号：
06650027
负责人：
HORINAKA Hiromichi
金额：
$ 1.09万
依托单位：
Osaka Prefecture University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

1. GaAs quantum wire structure was proposed as a new photocathode of polarized electron source with high polarization and high quantum efficiency. The anodization was carried out using a (111) oriented p-GaAs substrate (1x10^<18>cm^<-3> : Zn doped) under the conditions of HF concentration of 5-30%, current density of 20-200mA/cm^2 and immersion time of 2-5min. High density and low-size triangle poles (40-90nm in width) were obtained by this simple method when HF concentration was 25%, immersion time 2mins and current density 150mA/cm^2. The shift of the band edge and the splitting of valence band were predicted on the assumption that the quantum wire had the circular cross section.2. The circular polarization of photoluminescence of the p-GaAs quantum wire samples fabricated by anodization method was measured on the excitation of circularly polarized light. Peaks appeared at the higher energy side of the band edge of bulk GaAs in the luminescence polarization spectra. The luminescence polarization exceeded 25% which was the maximum value obtained in bulk GaAs. The luminescence polarization depends on the spin polarization of the conduction band electrons and the splitting of the valence band. These peaks and the enhancement of luminescence polarization were thought to be due to by the band edge shift and the splitting of the valence band.3. The luminescence polarization method using a streak camera is applied to the measurement of the spin relaxation time and the life time of electrons of samples. The temperature dependence of the spin relaxation time of the strained GaAs sample was measured. Electron-hole scattering is thought to be the main mechanism of the spin relaxation of our strained-GaAs photocathode. The spin relaxation time of GaAs quantum wire samples fabricated by the anodization method was measured by using the same method. It was found that the anodized p-GaAs sample had the long spin relaxation time in comparison with original substrate.

1。提出GAAS量子结构作为具有高极化和高量子效率的极化电子源的新光电模。在HF浓度为5-30％的条件下，使用（1x10^<18> cm^3>：Zn掺杂）使用（111）方向的P-GAAS底物（1x10^<18> cm^3>：Zn）进行阳极化。 CM^2，沉浸时间为2-5min。当HF浓度为25％，浸入时间2分钟和电流密度150mA/cm^2时，通过这种简单方法获得了高密度和低尺寸三角极（宽度为40-90nm）。假设量子线具有圆形横截面2。在圆形极化光的激发上测量了通过阳极化方法制造的P-GAAS量子线样品的光致发光的圆极化。峰出现在发光极化光谱中散装GAA的带边缘的较高能量侧。发光偏振超过25％，这是在散装GAA中获得的最大值。发光极化取决于传导带电子的自旋极化和价带的分裂。这些峰和发光极化的增强被认为是由于带边缘移位和价带的分裂造成的。3。使用条纹摄像机的发光偏振法应用于自旋松弛时间和样品电子寿命的测量。测量应变GAAS样品的自旋松弛时间的温度依赖性。电子 - 孔散射被认为是我们应变的-GAAS光电阴道自旋松弛的主要机制。使用相同的方法测量了由阳极氧化方法制造的GAAS量子线样品的自旋松弛时间。发现与原始底物相比，阳极氧化的P-GAAS样品的自旋松弛时间很长。