GaN外延结构中微区应变场的测量和评价

 采用电子背散射衍射(EBSD)技术,测量GaN/蓝宝石结构中的弹性应变场.将EBSD菊池衍射花样的图像质量IQ值及小角度错配作为应力敏感参数,表征GaN-Buffer层-蓝宝石结构中的晶格畸变和转动,显示微区弹性应变场.在GaN/蓝宝石系统中,弹性应变的影响范围大约200×700nm.采用快速傅立叶变换(FFT)提取菊池花样的衍射强度,识别GaN外延结构中的应变/无应变区域.

Measurement and Evaluation of Micro-Sized Strain Fields in GaN Epitaxial Structure

The elastic strain field in a GaN/sapphire structure was measured via electron backscatter diffraction (EBSD).Image quality and small misorientation of EBSD Kikuchi patterns as strain sensitive parameters were applied to evaluate the distortion and the rotation of crystal lattices in GaN-buffer-sapphire structure,as well as to display micro-sized elastic strain field.The influence region of the elastic strain in GaN/sapphire structure is about 200×700 nm.The diffraction intensities of Kikuchi patterns were extracted and the strained/unstrained regions in GaN epitaxial structure were recognized by using the fast Fourier transform (FFT).