An analytical model for estimation of the stress field and cracks caused by scratching anisotropic single crystal gallium nitride

Single crystal gallium nitride will produce subsurface damage during processing, and studying the total stress field during scratching gallium nitride is advantageous for predicting and controlling subsurface damage. The total stress field during scratching gallium nitride (0001) crystal plane is obtained by superimposing the elastic and residual stress field. Thus the distribution of the stress field under the indenter can be acquired. It was found that the median crack nucleated at the elastoplastic interface of the front of the indenter, and the extension angle of the median crack is linearly related to half-angle of the conical indenter. Next the anisotropic model in this paper and the method simplified to isotropic materials are used for calculating the total stress field, and the consequences of the two are obviously different. The ratio between the stresses obtained by the two methods under different indenter half-angle has been obtained. Then by introducing the corresponding ratio into the traditional equation of the median crack depth and the lateral crack depth, the results considering the anisotropy can be obtained by the isotropic method.

Automated summary

Investigation shows that the distribution of total stress field during scratching gallium nitride affects the initiation and extension of cracks. By introducing an anisotropic model, the results obtained are significantly different from the method simplified to isotropic materials.