NATIVE POINT-DEFECTS IN TE-RICH P-TYPE HG1-XCDXTE

The stability regions of Te-rich p-conducting Hg1-xCdxTe with x = 0.20, 0.28 and 0.38 were investigated by means of high-temperature in situ Hall and conductivity measurements. The Te-rich limits of the p-side stability regions, measured in situ, correspond to higher electrically active native point defect concentrations than reported in the literature for quenched samples. In the temperature range 300 less-than-or-equal-to T less-than-or-equal-to 900 K, there is a linear relationship between the reciprocal temperature and the logarithm of electrically active native acceptor concentrations. We conclude that only one predominant kind of native point defect exists, probably the mercury vacancy V(Hg). Its defect formation energies are calculated. The assumption of Hg vacancies as the predominant kind of defects is supported by precision measurements of lattice parameters, which decrease with increasing defect concentration. From these investigations we conclude that a considerably greater number of defects exist than are electrically measurable, especially at higher Cd contents.