A NEW ETCHANT TO REVEAL THE SUBSURFACE DAMAGE ON POLISHED GALLIUM-ARSENIDE SUBSTRATES

In the present investigations, a new etchant, viz., Bi(NO3)(3)-H2O2-HC l (''BNCL etchant'') has been established for GaAs to reveal the subsu rface damage induced during the polishing procedures. The investigated (1 0 0) oriented, silicon-doped n-type GaAs and undoped semi-insulati ng GaAs wafers were polished with slurries having pH 8 and 9. After et ching, the shallow scratches are visible in addition to the wave-like defects. The etching rate was 6.5 mu m/min for n-type and 8 mu m/min f or semi-insulating. When the etching was carried out for 2 min, all th e observed damage vanished and most of the surface of both (n-type and semi-insulating) samples were found to be uniformly etched. The capab ility of the etchant to reveal the subsurface damage has been confirme d.