Study of lateral growth regions in ammonothermal c-plane GaN

Lateral growth in the a-direction is an effective way to expand the size of crystal in basic ammonothermal GaN growth. Cathodoluminescence image of cross section clearly revealed several different regions along a-direction. Stress distributions and optical properties were investigated among these different regions by Raman spectroscopy and photoluminescence spectroscopy, respectively. TOF-SIMS mapping showed the spatial distribution of O, H, Si and C impurities in lateral growth regions. Our results indicate that there is small stress variation among the interfaces. Different concentration of impurities incorporated in these regions, especially O impurity, which can significantly increase the free carrier concentration. Fairly low concentration and uniform distribution of C impurity indicated that YL band in PL spectra is not closely related to carbon impurity or a complex involving carbon. Based on the above data, the evolution process of lateral crystal growth is deduced.

Automated summary

The lateral growth in the a-direction is an effective method to expand the crystal size in basic ammonothermal GaN growth. Different stress distributions and optical properties were found among distinct regions, along with varying impurity concentrations. The findings indicate a small stress variation among interfaces and suggest the evolution process of lateral crystal growth.