多晶硅薄膜电学输运理论的研究进展

Research progress on carrier transport theory of polycrystalline silicon thin films

多晶硅薄膜已广泛应用于平板显示、微机电系统和集成电路等领域,在太阳电池和平板系统领域也有着巨大的应用前景。由于多晶硅薄膜存在晶界,晶界内的晶体缺陷和悬挂键会向带隙中引入界面态,界面态一方面会束缚载流子并形成势垒阻碍载流子的传输,另一方面会作为有效复合中心加重载流子的复合,因此,多晶硅薄膜上制备的器件的性能要低于与之对应的单晶硅薄膜器件的性能。为了从理论上阐明暗场和光照条件下多晶硅薄膜的电学性质,人们已发展了各种理论模型。此外,为了确定晶界界面态在带隙中的分布,人们已发展出分析法和计算机模拟两种方法。本文将简要概述人们在多晶硅薄膜电学输运理论和晶界界面态分布确定方法等方面的主要研究进展,以期对从事多晶硅薄膜或多晶半导体输运性质研究的科研工作者有所参考和启发。

Polycrystalline silicon （poly-Si） thin films have been widely used in flat panel displays,MEMS（micro-electro-mechanical system） and integrated circuits,and also have great application prospects in other areas such as solar cells and SOP （system on panel）.Since there exist grain boundaries （GBs） in poly-Si thin films,the crystal defects and dangling bonds in GB regions would introduce interface states in the band gap.On the one hand,the interface states would trap carriers thus creating barriers against carrier transportation,on the other hand,they could act as effective recombination centers to strengthen the recombination.Therefore,the performance of devices fabricated on poly-Si thin films is generally worse than that on single-crystal silicon thin films.To give a theoretical explanation on the electrical properties of poly-Si thin films under the dark and illumination conditions,various theoretical models have been proposed.In addition,two kinds of ways including analytical method and computer simulation have been developed to determine the energy distribution of interface states in the band gap.This article will briefly review the major research progress in electrical transport theory of poly-Si films and methods for determining the distribution of the interface states,so that researchers engaging in investigation on transport properties of poly-Si thin films or polycrystalline semiconductors could get some reference and inspiration.