AlN缓冲层对Si基GaN外延薄膜性质的影响

Influence of AlN Buffer Layer on Properties of GaN Epitaxial Film Grown on Si Substrate

采用金属有机化合物化学气相沉积(MOCVD)方法制备了不同AlN缓冲层厚度的GaN样品,研究了AlN缓冲层厚度对GaN外延层的应力、表面形貌和晶体质量的影响。研究结果表明:厚度为15 nm的AlN缓冲层不仅可以有效抑制Si扩散,而且还给GaN外延层提供了一个较大的压应力,避免GaN薄膜出现裂纹。在该厚度AlN缓冲层上制备的GaN薄膜表面光亮、无裂纹,受到的张应力为0.3 GPa,(0002)和(1012)面的高分辨X射线衍射摇摆曲线峰值半高宽分别为536 arcsec和594 arcsec,原子力显微镜测试得到表面粗糙度为0.2 nm。

GaN epitaxial films with different thickness of AlN buffer layers were grown on Si (111) by metal-organic chemical vapor deposition (MOCVD). The effects of AlN buffer thickness on in-plane stress, surface morphology and crystal quality of GaN materials were investigated. It is observed that the AlN buffer with thickness of 15 nm can effectively suppress the diffusion of Si from the substrate. Moreover, the AlN buffer can also introduce a relatively large compressive stress to GaN layers and eliminate the crack. The crack-free and mirror-like GaN layer was obtained by depositing on the AlN buffer layer with thickness of 15 nm. The full width at half maximum of the film is as low as 536 arcsec for (0002) and 594 arcsec for (101¯2) reflection, the in-plane tension stress is 0.3 GPa, and the RMS roughness tested by atomic force microscopy is 0.2 nm.