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

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The results of Hg1-xCdxTe layer growth by liquid phase epitaxy (LPE) from the Te-rich solution (Hg1-zCdz)1-yTey 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, $x=0.20{\mbox{--}}0.22$, and thicknesses ranging from 10 to 20 μm, which are suitable for manufacturing IR photodiode structures, were grown on (111) B-oriented Cd0.96Zn0,04Te substrates at 501--470 °C 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 ($\Delta\Theta\pm 1.8$ °C) and epilayer composition ($\Delta x\pm 0.003$) 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 $4\times 10^{16}$ to $1.4\times 10^{17}$ cm-3 and mobility of 240--270 cm2 V-1 s-1. The concentration and mobility of charge carriers in the layers annealed at 280 °C for 10 h under Hg overpressure were found to be $5\times 10^{15}$ cm-3 and $1\times 10^{4}$ cm2 V-1 s-1, respectively.
2011-05-25