气流混合对生长GaN∶Si膜性能影响的研究

Properties Dependence of GaN∶Si Films on Gas Flow Mixture

用金属有机化学气相沉积技术在三种不同型号的反应管中生长了GaN∶Si膜。通过对样品的光电及结晶性能的分析 ,研究了气流混合时间不同对GaN∶Si膜性质的影响。结果表明 :合理的Ⅲ、Ⅴ族气流混合对提高GaN∶Si膜的光电及结晶性能很重要。Ⅲ、Ⅴ族气流混合太早 ,气流混合时间长 ,GaN∶Si膜的黄带与带边发射强度之比较大 ,X射线双晶衍射半高宽较宽 ;Ⅲ、Ⅴ族气流混合太晚 ,尽管可减少预反应 ,但气流混合不均匀 ,致使GaN∶Si膜的发光性能及结晶性能变差。使用Ⅲ、Ⅴ族气流混合适中的反应管B生长 ,获得了光电及结晶性能良好的GaN∶Si单晶膜。

The GaN∶Si films were grown by MOCVD methods on (0001) sapphire substrates by using three different reactors. The opto-electrical and crystalline characterization of GaN∶Si films were measured by photoluminescene (PL), Van der Pauw Hall method and X-ray double crystal diffraction technique at room temperature, respectively. The results indicate that reasonable mixture time of group Ⅲ and groupⅤgas flows is important to improve the quality of GaN∶Si films. When group Ⅲ precursor mixes too early with groupⅤammonia, in other word, the time of the mixture is too long, the ratio of yellow luminescence intensity to band emission intensity is large, and the FWHM of X-ray double crystal diffraction is broad. When group Ⅲ precursor mixes too late with group Ⅴ ammonia, it will cause the opto-electrical and crystalline properties of GaN∶Si films poor due to inhomogeneous mixture even though the parasitic reaction became weak. GaN∶Si films with good opto-electrical and crystalline properties are obtained in B-type reactor.