多孔硅发光中的极化子效应

多孔硅体现了许多新光学性质，本文通过温度依赖的发光，傅立叶红外谱，时间分辨红外谱的观察。发现了些有规律的信息。众所周知，多孔硅在空气中陈化氧化，导致内部纳米尺寸减小。界面层由氢变为氧，我们发现同时伴随着电子态从本征态向极化子态的变化，前者随尺寸减小能量升高，表现为正常的量子限域效应。而后者却随尺寸减小能量降低。表现为量子限域极化子效应。温度依赖的发光谱型和强度变化也清楚地反映了尺寸依赖的极化子行为。因此，我们提出了个基本的物理模型来描述多孔硅中增强的极化子尺寸效应及其光学行为。

Confined Polaron Effect in the Photoluminescence of Porous Silicon

Porous silicon(PS) shows a variety of optical properties. In this report temperature dependent photoluminescence, Fourier Transformation Infrared spectra and time-resolved FTIR spectra of freshly prepared porous silicon(PS) and oxidized PS, are examined. The spectra of porous silicon samples with different aging time prove there occurred a gradual transformation of one state(intrinsic band transition) to another state(extrinsic polaronic state) along with aging it in air as aging lead to the surface oxidation and size reduction of Si nanostructures. The surface capping variation from H to O during aging in PS produce green and orange or red emission respectively. Clear quantum-confinement effects for both states are observed. The emissions in oxygen-capped PS show clear polaronic, not free carrier in fresh system, nature. The temperature dependent emission profile and intensities show clear temperature, oxidation and size dependent behaviors in porous silicon. These phenomena can be scaled by polaron related double-potential-well model to describe the electronic state redistribution and spectroscopic behavior in oxidized PS. This model indicates that an enhanced polarons near surface exist as the size of silicon decrease. A equation from this model is in good agreement with the experimental results of porous silicon samples of different sizes.