Traces of HgCdTe Defects as Revealed by Etch Pits

Abstract

The characteristics of defects in HgCdTe liquid-phase epitaxy (LPE) epilayers were investigated by using Schaake’s and Chen’s etches. By tracking the etch pits (EP), two kinds of threading dislocations with <110> and <211> orientations were observed for the first time in HgCdTe LPE epilayers. They are ascribed to perfect 60 deg dislocation and Shockley partial screw dislocations. The kinds of dislocation etch pits revealed by Schaake’s and Chen’s etches were experimentally confirmed to be correlated one-to-one. In addition to the threading dislocation etch pits, another kind of etch pits without the threading feature was also observed using both etch methods. The density of the nonthreading etch pits increases in the regions close to epilayer-substrate interfaces, scratched areas, and melt droplets. The etch pit density (EPD) varies from 10⁴ cm⁻² to 10⁷ cm⁻² from sample to sample or at different places on the same sample, indicating that they are correlated to stresses and should be considered in the assessment of HgCdTe epilayers.