脉冲激光在SiGe合金样品表面可以形成量子点结构。样品退火处理后,在720-800 nm光谱区域内存在一些受激发射峰,并且这些受激发射峰有明显的阈值行为。实验发现从Si量子点到SiGe量子点结构的变化将导致受激发光峰有明显的红移现象。由傅里叶变换红外光谱仪(FTIR)分析得到:SiGe合金上氧化层中的量子点同时含有Si=O和Ge=O双键结构,这种结构可以形成电子的局域陷阱态(或陷阱态的激子)。计算显示:在SiGe量子点中Ge=O双键可以减小半导体样品中价带和局域陷阱态之间的距离。这就解释了SiGe量子点受激发射的红移现象。

Fabrication of quantum dots (QD) by pulsed laser on SiGe alloy samples is reported. After annealing,some peaks of stimulated emission were observed in the region of 720-800 nm which have threshold behavior obviously. It was found that the peaks of stimulated emission have an obvious red-shift from Si QD to SiGe QD. Oxide layer on SiGe quantum dots involves Si＝O bonds and Ge＝O bonds according to the Fourier transform infrared spectroscopy (FTIR),which could produce the localized gap states of electrons (or even the trapped exciton). Calculation shows that Ge＝O bonds emerging on SiGe QD could decrease the distance between the valence band and the localized gap states which can interpret the red-shift of stimulated emission on SiGe QD.