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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。
Pulsed laser can form quantum dot structure on the surface of SiGe alloy sample. After annealing, there are some stimulated emission peaks in the 720-800 nm spectral range, and these stimulated emission peaks have obvious threshold behavior. It is found that the change of structure from Si quantum dots to SiGe quantum dots will lead to obvious red shift of the excited light peak. The results of Fourier transform infrared spectroscopy (FTIR) showed that the quantum dots in the oxide layer of SiGe alloy contain both Si = O and Ge = O double bond structures. This structure can form electron localized trap state (or trap state Of excitons). Calculations show that Ge = O double bonds in SiGe quantum dots can reduce the distance between valence band and local trap states in the semiconductor sample. This explains the redshift of stimulated SiGe quantum dots.