STUDY OF A NEW CHEMICAL ETCHANT FOR GASB (100)-SUBSTRATE AND (111)-SUBSTRATE PREPARATION FOR EPITAXIAL-GROWTH

A new chemical etchant for ex situ GaSb substrate preparation for epitaxial growth is proposed. The etchant utilizes components water solutions of d,l-tartaric acid C4H6O6 (5M, 20 degrees C), H2O2 (9.7M), and HF (23M). Various volume ratios of these components have been tested, resulting in controllable etch rates in the range from 0.5 to 4 mu/min. The obtained surfaces are mirror-like, smooth, and free from etch pits as revealed by scanning electron microscopy observations. The proposed etchant in 20:10:1 volume ratio is compared with the Br-2-methanol and CH3COOH:HNO3:HF (40:18:2) etchants with respect to the content of residual Sb2O3 and Ga2O3 and their thickness using x-ray photoelectron spectroscopy. The C4H6O6:H2O2:HF (20:10:1) etchant appears to be superior to the CH3COOH:HNO3:HF (40:18:2) one due to the high reproducibility of the obtained surfaces.