多孔硅拉曼光谱随激发功率变化的研究

用阳极氧化法新制备了多孔硅样品，以457．5nm固体激光器为激发光源，在不同激发功率下，获得了拉曼谱图和一些谱峰参量随激光功率的变化关系。解释了520cm^-1和300cm^-1附近拉曼峰随功率变化的一系列可逆的实验现象：随激光功率升高出现的红移和非对称性展宽，主要是由于样品局域平均粒径变小而受量子限域效应的影响导致的；样品局域平均粒径在表面上的二维减小与随激光功率升高而导致的局域温升并不违背基本的热力学定律；高功率时520cm^-1附近双峰的出现是由于多孔硅样品局域平均粒径达到一定阈值而导致的纵模和横模双声子模的分裂。

Dependence of the Raman Spectrum of Porous Silicon on Laser Power

Raman spectra of as-prepared porous silicon are obtained using 457.5 nm solid-state laser from which some relations between peak parameters and laser powers are also got.The experimental phenomena of the Raman peaks near 520 cm~(-1) and 300 cm~(-1) are extensively explained.The red-shift and asymmetrically broadening of the Raman peaks near 520 cm~(-1) and 300 cm~(-1),which are reversible with the increase and decrease of the laser powers,are thought to be derived from quantum confinement effect(QCE) when the mean particle size shrinks as local temperature increases,and this obeys the basic rule of thermodynamics.The apperarance of double peaks near(520 cm~(-1)) at high powers are thought to be the cleavage of longitudinal optical(LO) and transverse optical(TO) modes when the mean particle size reaches a certain threshold.