HVPE法生长GaN厚膜弯曲的分析

Analysis of the Curvature of GaN Thick Films Grown by HVPE

异质外延生长和降温过程中的失配会引起HVPE厚膜样品的弯曲,较大的弯曲会导致薄膜开裂和剥落。利用高分辨X射线衍射仪(XRD)分析,HVPE生长的不同厚度GaN样品的弯曲。对于同一个样品,X射线出射狭缝分别用1mm的标准狭缝和50μm的小狭缝测量,发现(0002)面摇摆曲线的半宽有明显变化。通过计算和比较,采用标准狭缝测得的(0002)面摇摆曲线的展宽是由弯曲和位错共同引起的,而弯曲表现得更为显著,小狭缝的展宽主要反应样品位错的信息。通过不同狭缝半宽的测量,得到了不同厚度GaN厚膜样品的曲率和位错密度。

The bending of GaN thick films due to the thermal mismatch in cooling down process is a crucial problem in hydride vapor phase epitaxy(HVPE)growth.The curvature of GaN thick films by high resolution X-ray diffraction(HRXRD)was investigated.For the full width at half maximum(FWHM)around(0002)direction omega scan by using 1 mm and 50 μm slit incident beam,respectively,and two different results for every sample were got.It is found that the broadened FWHM by using 1 mm slit is the complex result between the bending and dislocations,and the broaden FWHM by using 50 μm is mainly due to the dislocations.The curvature and dislocation density of GaN thick films can be together obtained by using two kinds of incident beam slit in XRD measurement.