氢化非晶硅薄膜的红外光谱分析和桥键氢扩散假设(英文)

Analysis of IR transmission spectra and hypothesis of bond-centered H diffusion in a-Si∶H thin films during light-induced thermal annealing

通过红外透射光谱研究了在光诱导退火中退火条件对氢化非晶硅薄膜的结构和光电特性的影响,实验所用样品采用热丝辅助微波电子回旋共振化学气相沉积方法制备。我们用桥键氢扩散模型来解释退火中的不同现象。样品的红外光谱在630和2000cm-1处的吸收系数有所增加,说明了原先的成键氢发生了移动和溢出,我们认为通过光诱导产生载流子的非辐射复合以及桥键氢和深俘获氢原子的交换,产生了大量的桥键氢原子,它们相互结合形成分子氢,氢溢出要优于氢团聚。

The effect of light-induced thermal annealing at low temperature on the structure and electronic properties of hydrogenated amorphous silicon (a-Si: H) as a function of annealing conditions was studied by FTIR spectra method. The deposition of a-Si: H films was performed by using microwave electron cyclotron resonance (MW ECR) plasma with the assistance of tungsten filament. In this study, the infrared spectroscopy results show the interesting changes under the different annealing condition. The increase in the transmission coefficient at both 630 and 2000 cm-1 indicates that bonded hydrogen moved and effused from the amorphous network. The bond-centered (BC) H diffusion model is used to explain the H elimination phenomenon, we argue that the BC H atoms formed by the nonradiative recombination of photo-induced carriers and the exchange between BC H and deeply trapped H produce more and more BC H atoms, the BC H atoms will recombine each other and form molecular hydrogen, the process of H elimination is prior to monohydride clustering and/or bonds switching.