Al沉积时间对Si衬底GaN材料的影响

Effect of Duration of Al Deposition on GaN Epilayers Grown on Si Substrates

通过改变高温AlN形核层生长时提前通入TMAl的时间,分别在Si(111)衬底上生长了4个1μm厚的GaN样品,并对每个样品的GaN外延材料进行了分析研究。通过显微镜观察发现,Al的沉积时间为12 s时,GaN材料表面光亮,基本没有裂纹。另外通过喇曼谱和光荧光谱(PL)测试得出,随着生长初期Al沉积时间的增加(8～15 s),GaN外延层的水平应力逐渐减小(由1.28 GPa减小到0.67 GPa),Al的沉积时间为12 s时GaN外延材料的应力较小。同时,GaN材料(002)和(102)晶面的X射线衍射摇摆曲线表明,Al的沉积时间为12 s时GaN外延材料的晶体质量最好。

The four GaN samples of 1 μm thickness with different duration of Al deposition were grown on Si（111）substrates by metal-oganic chemical vapor deposition（MOCVD）.Analysis of the GaN epilayers was performed by microscope,Raman spectra,room-temperature photoluminescence（PL）and X-ray diffraction（XRD）.When the duration of Al deposition is 12 s,rarely cracked GaN epilayers with mirror surface were obtained,and the quality of the GaN epilayer is the best.Raman spectra show that the stress of GaN epilayer is reduced from 1.28 to 0.67 GPa while the duration of Al deposition increased from 8 to 15 s.The reduction in the stress was also confirmed by the room-temperature photoluminescence.