Evaluation of Composition Reproducibility of HgCdTe Epitaxial Layers Grown in Novel Liquid Phase Epitaxy Apparatus

摘要

The results of Hg_(1-x)Cd_xTe layer growth by liquid phase epitaxy (LPE) from the Te-rich solution (Hg_(1-z)Cd_z)_(1-y)Te_y with z = 0.0545 and y = 0.806 obtained by the tipping method in a closed system are presented. The epitaxial layers with different compositions, x = 0.20-0.22, and thicknesses ranging from 10 to 20μm, which are suitable for manufacturing IR photodiode structures, were grown on (111) B-oriented Cd_(0.96)Zn_(0.04)Te substrates at 501-470 ℃ in a sealed quartz ampoule. A novel LPE apparatus for obtaining of a residual-melt-drop-free surface is described. The effect of the preliminary synthesis of the source on the reproducibility of both the liquidus temperature (ΔH ± 1.8℃) and epilayer composition (Δx ± 0.003) was evaluated using the expression for the Hg-Cd-Te phase diagram. As-grown layers exhibit p-type conductivity with a carrier concentration in the range from 4 × 10~(16) to 1.4 × 10~(17)cm~(-3) and mobility of 240-270cm~2 V~(-1) s~(-1). The concentration and mobility of charge carriers in the layers annealed at 280℃ for 10h under Hg overpressure were found to be 5 × 10~(15)cm~(-3) and 1 × 10~4cm~2 V~(-1) s~(-1), respectively.