光学 精密工程, 2018, 26 (8): 1960, 网络出版: 2018-10-02
纳米硅氧多层薄膜低温调控及其发光特性
Low temperature deposition and photoluminescence properties of silicon oxide multilayer films
纳米硅氧多层薄膜 微观结构 能带特征 光致发光 量子限制效应 silicon oxide multilayer films microstructure energy band photoluminescence quantum confinement effect
摘要
为了研究硅量子点薄膜在太阳电池中的应用, 本文采用甚高频等离子体增强化学气相沉积技术, 低温制备了镶嵌有纳米晶硅(nc-Si)的纳米硅氧多层(nc-SiOx/a-SiOx)薄膜样品。TEM图显示, 通过调整nc-SiOx层的厚度, 实现了薄膜多层结构的低温调控。利用拉曼散射光谱(Raman)、紫外可见透射光谱以及稳/瞬态光致发光(PL)谱等检测手段对薄膜的微观结构、能带特征以及发光特性进行了分析。光吸收谱分析表明, nc-Si粒子尺寸及其a-SiOx边界层共同影响薄膜的光学带隙。稳/瞬态PL谱分析表明, 多层结构发光表现为一个固定于1.19 eV附近的发光峰和一个随nc-SiOx层厚度增加而发生红移的发光峰, 其中固定发光峰归因于非晶SiOx网络中缺陷发光, 发光衰减寿命约在4.6 μs, 峰位可调的发光峰为nc-Si量子限制效应-缺陷态复合发光, 对应两个发光衰减过程, 其中慢发光衰减寿命随nc-SiOx层厚度增加由9.9 μs增加到16.5 μs, 快发光衰减过程基本保持不变。低温PL谱的温度依赖特性进一步表明, 薄膜样品的发光主要表现为nc-Si的量子限制效应发光。
Abstract
Nc-SiOx/a-SiOx multilayer films were deposited using very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD), to investigate the application of silicon quantum dots in solar cells. Transmission electron microscopy (TEM) images revealed that a multilayer structure was achieved by adjusting the thickness of the nc-SiOx layer at low temperature. Based on Raman scattering, UV-visible transmission, and steady/transient photoluminescence (PL) spectra, the microstructure, energy band, and photoluminescence properties of the films were characterized, respectively. Absorption spectra analysis indicated that the combination of the nc-Si and a-SiOx matrices affected the optical band gap of the films. The PL spectra of the multilayer films exhibited two distinct peaks as the thickness of the nc-SiOx layer was increased: a peak fixed at 1.19 eV, and another red-shifted peak near 1.45 eV. The fixed PL peak originated from radiative defects in the a-SiOx matrix, which corresponds to a PL decay life of approximately 4.6 μs. The red-shifted PL peak was attributed to a complex quantum confinement effect-defect state luminescence mechanism. This is related to two PL decay processes including a slow PL decay life, which increased from 9.9 to 16.5 μs, and a fast decay life, which was constant. The temperature-dependent PL properties further signified that the origin of the PL of the multilayer films was mainly attributed to quantum confinement effects in nc-Si.
李云, 张博惠, 高东泽, 丛日东, 于威, 路万兵. 纳米硅氧多层薄膜低温调控及其发光特性[J]. 光学 精密工程, 2018, 26(8): 1960. LI Yun, ZHANG Bo-hui, GAO Dong-ze, CONG Ri-dong, YU Wei, LU Wan-bing. Low temperature deposition and photoluminescence properties of silicon oxide multilayer films[J]. Optics and Precision Engineering, 2018, 26(8): 1960.