Nonselective etching of GaN/AlGaN heterostructures by Cl2/Ar/BCl3 inductively coupled plasmas

Nonselective etching of GaN/AlGaN heterostructures by Cl_2/Ar/BCl_3 inuctively coupled plasmas

A systematic study of the nonselective and smooth etching of GaN/AIGaN het-erostructures was performed using C12/Ar/BCI3 inductively coupled plasmas (ICR).Nonselective etching can be realized by adjusting the BCI3 ratio in the Cl2/Ar/BCI3 mixture (20%—60%), increasing the ICR power and dc bias, and decreasing the chamber pressure. Surface morphology of the etched heterostructures strongly depends on the gas chemistry and the chamber pressure. Specifically, with the addition of 20% BCI3 to Cl2/Ar (4:1) gas mixture, nonselective etching of GaN/Al0.28Ga0.72N heterostructures at high etch rate is maintained and the surface root-mean-square (rms) roughness is reduced from 10.622 to 0.495 nm, which is smoother than the as-grown sample. Auger electron spectroscopy (AES) analysis shows that the effective removal of residual oxygen from the surface of AIGaN during the etching process is crucial to the nonselective and smooth etching of GaN/AIGaN herterostructures at high etch rate.

A systematic study of the nonselective and smooth etching of GaN/AlGaN heterostructures was performed using Cl2/Ar/BCl3 inductively coupled plasmas (ICP). Nonselective etching can be realized by adjusting the BCl3 ratio in the Cl2/Ar/BCl3 mixture (20%–60%), increasing the ICP power and dc bias, and decreasing the chamber pressure. Surface morphology of the etched heterostructures strongly depends on the gas chemistry and the chamber pressure. Specifically, with the addition of 20% BCl3 to Cl2/Ar (4∶1) gas mixture, nonselective etching of GaN/Al0.28Ga0.72N heterostructures at high etch rate is maintained and the surface root-mean-square (rms) roughness is reduced from 10.622 to 0.495 nm, which is smoother than the as-grown sample. Auger electron spectroscopy (AES) analysis shows that the effective removal of residual oxygen from the surface of AlGaN during the etching process is crucial to the nonselective and smooth etching of GaN/AlGaN herterostructures at high etch rate. Keywords GaN - Al0.28Ga0.72N - ICP - Cl2/Ar/BCl3 - nonselective etching