快速热退火和氢等离子体处理对富硅氧化硅薄膜微结构与发光的影响

Effect of rapid thermal annealing and hydrogen plasma treatment on the microstructure and light-emission of silicon-rich oxide film

采用micro Raman散射、傅里叶变换红外吸收谱和光致发光谱研究了快速热退火及氢等离子体处理对等离子体增强化学气相沉积法 2 0 0℃衬底温度下生长的富硅氧化硅 (SRSO)薄膜微结构和发光的影响 .研究发现 ,在 30 0—6 0 0℃范围内退火 ,SRSO薄膜中非晶硅和SiOx∶H两相之间的相分离程度随退火温度升高趋于减小 ;而在 6 0 0—90 0℃范围内退火 ,其相分离程度随退火温度升高又趋于增大 ;同时发现SRSO薄膜发光先是随退火温度的升高显著加强 ,然后在退火温度达到和超过 6 0 0℃后迅速减弱 ;发光峰位在 30 0℃退火后蓝移 ,此后随退火温度升高逐渐红移 .对不同温度退火后的薄膜进行氢等离子体处理 ,发光强度不同程度有所增强 ,发光峰位有所移动 ,但不同温度退火样品发光增强的幅度和峰位移动的趋势不同 .分析认为退火能够引起薄膜中非晶硅颗粒尺度、颗粒表面结构状态以及氢的存在和分布等方面的变化 .结果表明不仅颗粒的尺度大小 ,而且颗粒表面的结构状态都对非晶硅颗粒能带结构和光生载流子复合机理发挥重要影响 .

Silicon-rich silicon oxide (SRSO) films are prepared by plasma-enhanced chemical vapor deposition method at the substrate temperature of 200degreesC. The effect of rapid thermal annealing and hydrogen plasma treatment on tire microstructure and light-emission of SRSO films are investigated in detail using micro-Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and photoluminescence (PL) spectra. It is found that the phase-separation degree of the films decreases with increasing annealing temperature from 300 to 600degreesC, while it increases with increasing annealing temperature from 600 to 900degreesC. The light-emission of the films are enhanced with increasing annealing temperature up to 500degreesC, while it is rapidly reduced when the annealing temperature exceeds 600degreesC. The peak position of the PL spectrum blueshifts by annealing at the temperature of 300degreesC, then it red-shifts with further raising annealing temperature. The following hydrogen plasma treatment results in a disproportionate increase of the PL intensity and a blueshift or redshift of the peak positions, depending on the pristine annealing temperature. It is thought that the size of amorphous silicon clusters, surface structure of the clusters and the distribution of hydrogen in the films can be changed during the annealing procedure. The results indicate that not only cluster size but also surface state of the clusters plays an important role in the determination of electronic structure of the amorphous silicon cluster and recombination process of light-generated carriers.