蓝宝石衬底上HVPE-GaN厚膜生长

采用氢化物气相外延(HVPE)方法,以蓝宝石作衬底,分别在MOCVD-GaN模板和蓝宝石衬底上直接外延生长GaN.模板上的GaN生长表面平整、光亮,但开裂严重.其(0002)的双晶衍射半高宽最低为141″;蓝宝石衬底上直接生长GaN外延层质量较差,其双晶衍射半高宽为1688″,但不发生开裂.HCl的载气流量对预反应有很大的影响.应力产生于外延层和衬底之间的界面处,界面孔洞的存在可以释放应力,减少开裂.光致发光(PL)谱中氧杂质引起强黄光发射.

Growth of GaN Thick Film by HVPE on Sapphire Substrate

Growth of GaN film by HVPE was carried out on MOCVD-GaN template and sapphire substrate.The surface of GaN film grown on GaN template was flat and bright,but cracked heavily.The FWHM for GaN (0002) DCXRD is at least 141" .The quality of samples grown directly on sapphire substrate was poor,with a FWHM 1688" for GaN (0002),but it did not crack at all.The carrier gas flow rate was found to have a great effect on pre-reactions.Stress was produced at the interface between the epitaxial layer and the substrate.Holes at the interface can relax the stress greatly,which is helpful for reducing cracks.The yellow luminescence in the PL spectrum arose from O impurity.