退火对nc-Si镶嵌复合薄膜结构及发光特性的影响

Effect of annealing on microstructure and photoluminescence of nano-composite silicon film

采用减压化学气相沉积方法,依靠纯N2稀释的SiH4气体的热分解反应,在玻璃表面生长了纳米硅镶嵌的复合薄膜.实验研究了退火前后薄膜样品的结晶状态和光致发光特性.结果表明,未退火样品的光致发光特性随沉积温度升高反而减弱.当退火温度>600℃时,晶化趋势明显;当退火温度<600℃时,对晶化的影响不显著,但提高退火温度或延长退火时间可以增加光致发光谱(PL)强度.通过HRTEM分析证实了薄膜为纳米硅镶嵌复合的特殊结构.并通过Raman、PL、HRTEM的比较分析,认为在退火前后分别有两种不同的发光机制起主导作用.

A specially designed chemical vapor deposition （CVD） system with SiH4 as the source gas was constructed to grow nano-composition silicon films on glass substrate, The microstructure and photoluminescence of these films were systematically studied by measurements of micro-Raman, photoluminescence（PL） and high resolution transmission microscope （HRTEM）. The results show that the increasing deposition temperature decrease the PI. intensity of the as-deposited samples. The annealing temperature below 600 C don＇t strongly affect the crystallization. And increasing the annealing temperature or prolonging the annealing time enhances the PL intensity obviously. HRTEM analysis confirms that the film had a special nano-composite structure. Relevant investigation shows that two luminescence mechanisms can explain the different PL intensity of as-deposited and annealed samples.