The circularly polarized cathodoluminescence (CL) technique has been used to study the free spin-polarized electron injection in semiconductor heterostructures with quantum wells (QWs). A polarized electron beam was created by the emission of optically oriented electrons from the p-GaAs(Cs,O) negative electron affinity (NEA) photocathode. The prepared beam was injected in a semiconductor QW target, which was activated by cesium and oxygen to reduce the work function. To study the spin-dependent injection, we developed a spin-detector prototype, which consists of a compact proximity focused vacuum tube with the source and target placed parallel to each other on the opposite ends of the vacuum tube (photodiode). The injection of polarized low-energy electrons into the target by varying the kinetic energy in the range of 0.5-5.0 eV and temperature in the range of 90-300 K was studied. The CL was polarized to 2 % by the injection of 20 % spin-polarized electron beam with the energy of 0.5 eV at room temperature. The asymmetry (Sherman function) of spin detection was estimated. It was shown that the dependence of the CL polarization degree on the injected electron energy is satisfactory described by the model that considers the electron spin relaxation in the heterostructure matrix and QWs. The results demonstrate that semiconductor detectors are promising for the spin-polarimetry applications based on the optical detection of free-electron spin polarization.

中文翻译：

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半导体异质结构中自旋极化超低能电子的光谱检测

圆极化阴极发光 (CL) 技术已用于研究具有量子阱 (QW) 的半导体异质结构中的自由自旋极化电子注入。极化电子束是通过从 p-GaAs(Cs,O) 负电子亲和性 (NEA) 光电阴极发射光学定向电子而产生的。制备的光束被注入半导体 QW 靶中，该靶被铯和氧激活以降低功函数。为了研究与自旋相关的注入，我们开发了一个自旋探测器原型，它由一个紧凑的近距聚焦真空管组成，源和目标彼此平行放置在真空管（光电二极管）的相对两端。通过在 0.5-5 范围内改变动能，将极化的低能电子注入目标。研究了 0 eV 和 90-300 K 范围内的温度。通过在室温下注入能量为 0.5 eV 的 20% 自旋极化电子束，将 CL 极化到 2%。估计了自旋检测的不对称性（谢尔曼函数）。结果表明，CL极化程度对注入电子能量的依赖性通过考虑异质结构矩阵和QW中的电子自旋弛豫的模型得到令人满意的描述。结果表明，基于自由电子自旋极化的光学检测，半导体探测器有望用于自旋极化应用。估计了自旋检测的不对称性（谢尔曼函数）。结果表明，CL极化程度对注入电子能量的依赖性通过考虑异质结构矩阵和QW中的电子自旋弛豫的模型得到令人满意的描述。结果表明，基于自由电子自旋极化的光学检测，半导体探测器有望用于自旋极化应用。估计了自旋检测的不对称性（谢尔曼函数）。结果表明，CL极化程度对注入电子能量的依赖性通过考虑异质结构矩阵和QW中的电子自旋弛豫的模型得到令人满意的描述。结果表明，基于自由电子自旋极化的光学检测，半导体探测器有望用于自旋极化应用。