掩埋隧道结VCSEL芯片小信号等效电路模型

提出了适用于一种1.55μm掩埋隧道结垂直腔面发射激光器(VCSEL)芯片的小信号等效电路模型.等效电路的提出是基于半导体激光器速率方程以及VCSEL芯片结构,电路中各元件都有严格的物理意义.根据实验测得芯片的反射系数及传输参数,通过小信号等效电路仿真模拟,得到电路各元件参数值.不同偏置电流下,模拟结果与实验结果吻合都非常好,证明了该等效电路的有效性.

Electronic and vibrational Raman scattering in resonance with yellow luminescence transitions in GaN on sapphire substrate

We analyze low-temperature Raman and photoluminescence spectra of MBE-grown GaN layers on sapphire. Strong and sharp Raman peaks are observed in the low frequency region. These peaks, which are enhanced by excitation in resonance with yellow luminescence transitions, are attributed to electronic transitions related to shallow donor levels in hexagonal GaN. It is proposed that a low frequency Raman peak at 11.7 meV is caused by a pseudo-local vibration mode related to defects involved in yellow luminescence transitions. The dependence of the photoluminescence spectra on temperature gives additional information about the residual impurities in these GaN layers.