Characterization of GaAs (211) surface for epitaxial buffer growth

Abstract

GaAs (211)B wafer can be used for the growth of CdTe buffer layer by MBE after thermal desorption of oxide presents on its surface. Then, CdTe buffered GaAs (211)B called as composite substrate can be used as a template for the growth of HgCdTe. Thermal desorption can be detrimental to surface in some cases if the structure and constituents of this oxide are not fully understood. In this thesis, HF:H2O and H2SO4:H2O2:H2O chemical treatments were applied to epiready GaAs (211)B samples for the determination of suitability of their usage for CdTe buffer layer growth. Effects of these wet chemical etching processes on the surface of samples are characterized and determined by various kinds of characterization techniques including XRD, XPS, SEM, EDX, AFM, and optical microscope. We also analyzed samples cut from 3" epiready GaAs (211)B wafers to determine their oxide structures, surface roughnesses, crystal qualities, and surface morphologies. Crystal quality of as-received samples measured by RC were about 18-21 arcsec. Amounts of arsenic and gallium oxides were decreased after HF treatment according to XPS results. Gallium rich surface was obtained for samples treated with piranha solution. Surface roughnesses of samples increased after piranha treatment. However, it was determined that others treated with HF had smaller surface roughnesses than asreceived samples.