Abrasive Free Chemical Mechanical Planarization of Semi-Polar (11-22) GaN: Effect on Structural and Surface Properties and Subsequent Homoepitaxial Growth

作者：Parthiban P; Rahman A Azizur; Bhattacharya Arnab^*; Das D

来源：ECS Journal of Solid State Science and Technology, 2018, 7(4): P152-P157.

DOI：10.1149/2.0031804jss

The implementation of abrasive free chemical mechanical planarization (AFCMP) as an intermediate step to improve the structural and surface qualities of semi-polar (11-22) GaN device layer has been investigated. As-grown semi-polar (11-22) GaN surfaces were polished and characterized for surface finish using AFM and optical surface profiler to investigate the effect of surface planarity. Atomically flat surface with rms roughness of 4 angstrom was achieved over a scan area of 5 x 5 mu m(2) with a polishing rate of similar to 2.50 mu m/hr. Further, this polished wafer was used as a template for the homoepitaxial re-growth of semi-polar (11-22) GaN epilayer. In comparison to as-grown and polished surfaces, the re-grown surface showed a good crystal quality with a reduced full width at half maximum (FWHM) value of 535 arc sec, obtained from X-ray Rocking Curve (XRC) along [11-2-3] direction. Around 0.3 GPa of in-plane stress relaxation has been observed for the re-grown epilayer in comparison to as-grown surface further indicating the improved structural quality. An improved rms surface roughness (similar to 58% over a scan area of 1.26 x 0.90 mm(2)) has been achieved for the re-grown GaN epilayer (grown on the AFCMP treated atomically flat surface) as compared to the as-grown surface.

• 出版日期2018