激光促进多孔硅内表面氧化与光致发光的退化

本文对刚制备的以及分别经以下三种情况:1.样品在1大气压的氧气中经激光(Ar~+激光器的48.80nm线,功率密度为1.77W/cm~2)连续照射1小时;2.样品在1大气压的氧气中在没有激光照射的情况下保持1小时;3.样品在1.3×10~2Pa真空度下用激光连续照射1小时处理后的多孔硅在室温下进行了光致发光谱和傅里叶变换红外吸收测量,研究了处理前后光谱的变化。实验发现经第一种情况处理后光致发光峰位蓝移了约0.1eV,发光强度衰减了二十几倍,相应的其红外光谱中与氧有关的吸收峰强度大幅度增长,而经第二,三两种情况处理后它们的光致发光及红外吸收谱则无大的变化。研究表明在氧气中激光辐照能大大加速多孔硅内表面的氧化。我们认为很可能是多孔硅内表面的氧化作用使光致发光峰位蓝移,由氧化作用产生的非辐射复合中心导致光致发光效率的下降。

LASER ILLUMINATION INDUCED INNER SURFACE OXIDATION AND LUMINESCENCE DEGRADATION FOR POROUS SILICON

At room temperature we have measured photoluminescence (PL) and Fourier-Transform Infrared (FTIR) absorption spectra of porous silicon (PS) layers which were asgrown or treated separately in the following three ways for 1h: 1. In oxygen with continuous laser illumination (LI) (excitation with the 488.0nm line of argon ion laser with power density of 1.77W/cm~2). 2. In oxygen without LI. 3. In vacuum with LI. For treatment 1, we find that the PL peak of PS shows a blue shift of about 0.leV, the PL intensity decreases by a factor of more than twenty, and its IR absorption bands related to oxygen enhance greatly, however, in treatment 2 and 3, the PL and FTIR spectra vary very little. Experimental results show that the oxidation of inner surfaces of PS is accelerated greatly by LI in oxygen. The blue shift of the PL peak is a result of oxidation of inner surfaces of PS and the decrease of PL efficiency is attributed to the produce of nonradiative recombination centers during oxidation.