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经激光辐照和高温退火后能够在硅基上生成氧化多孔硅结构。用514 nm的激光泵浦,观测到该多孔硅的受激辐射。当激励强度超过阈值时,在650~750 nm区域有很强的受激发光峰。这些受激发光峰的半高宽小于0.5 nm。激光辐照和高温退火后,在样品上能形成某些特殊的氧化结构。在傅里叶红外光谱分析中,显示有硅氧双键或硅氧桥键在硅表面形成。计算结果表明:当硅氧双键或硅氧桥键形成时,电子的陷阱态出现在纳晶硅的带隙中。价带顶和陷阱态之间的粒子数反转是解释这种受激辐射的关键。
Oxidized porous silicon structures can be formed on silicon substrates by laser irradiation and high temperature annealing. Pumped by a 514 nm laser, the stimulated emission of the porous silicon was observed. When the excitation intensity exceeds the threshold, there is a strong stimulated emission peak in the region of 650-750 nm. The full width at half maximum of these stimulated luminescence peaks is less than 0.5 nm. After laser irradiation and high temperature annealing, some special oxidation structures can be formed on the sample. In Fourier transform infrared spectroscopy, a silicon double bond or a siloxane bridge was shown to form on the silicon surface. The calculated results show that when the double bond or silicon oxygen bridge is formed, the trap state of the electron appears in the band gap of the nanocrystalline silicon. The inversion of the number of vales between the valence band top and the trap state is the key to explaining this stimulated emission.