
Investigation of the aSi:H films by using thermal and lightinduced annealing treatment in atomic hydrogen atmosphere in HWECR CVD system
Zhu XiuHong, Chen GuangHua, Rong YanDong, Li Ying, Song XueMei, Zhou HuaiEn, Gao Zhuo, Ma ZhanJie, Deng JinXiang, Hu YueHui
Chin. Phys. B, 2005, 14 (7):
14571464.
DOI: 10.1088/10091963/14/7/034
To Investigate the stability of hydrogenated amorphous silicon (aSi:H) films, the thermal and lightinduced annealing treatment in an atomic hydrogen atmosphere (TLAH) is carried out by using a new hotwireassisted microwave electroncyclotronresonance chemical vapour deposition system (HWECR CVD) modified from a conventional microwave electronic cyclotron resonance chemical vapor deposition system (MWECR CVD). In order to compare with the TLAH method, the experiments of thermal annealing, and thermal and lightinduced annealing are also performed. Meanwhile, for the purpose of analysing the photoconductivity degradation quantitative, the photoconductivity degradation is assumed to obey the extended exponential law: 1/$\sigma _{\rm ph}$=1/$\sigma _{\rm s}$(1/$\sigma _{\rm s}$1/$\sigma
_{0})\exp[(t/\tau )^{\beta }$], where the extended exponential $\beta $ and the time constant $\tau $ are gained by the slope and the intercept of the line according to the linear relationship between $\ln \left( {  \ln \left( {\dfrac{\sigma _{\rm s}^{  1}  \sigma _{\rm ph}^{  1} }{\sigma
_{\rm s}^{  1}  \sigma _0^{  1} }} \right)} \right)$ and ln$t$, deduced from the extended
exponential law; the photoconductivity saturation value $\sigma _{\rm s}$ can be obtained by Gaussian fitting according to the relationship between photoconductivity and lightsoaking time in the logarithmic coordinate system. The experimental results show that the TLAH can improve the stability, microstructure and optoelectronic properties of the annealed aSi:H films, obviously decrease their optical band gaps, and remarkably move their photoluminescence spectrum (PL) peaks toward low energies.
