Comparison of Hg0.6Cd0.4Te LPE layer growth from Te-, Hg-, and HgTe-rich solutions

Hg
1-x
Cd
x
Te has been grown on CdTe substrates by liquid-phase epitaxy (LPE) from: 1) Te-rich solution at atmospheric pressure in a slider system, 2) Hg-rich solution in a sealed tube dipping system, and 3) HgTe-rich solution in sealed tube tipping and sliding systems. For epitaxial layers grown from Te-rich solution at 500°C, the width of the graded composition region is 3 µm and the compositional variation across the layer and with depth into the layers is less than ±0.01 mole fraction CdTe. The graded composition region for layers grown from Hg-rich solution at 460°C is less than 3 µm; however, there is no uniform composition region because of CdTe depletion from the melt. The graded bandgap region for pseudobinary growth at 700°C is much wider (20 µm) than the other two cases; however, a region of uniform composition can be obtained by growing sufficiently thick layers (> 30 µm). Pseudobinary growth has the theoretical advantage that either p-type or n-type layers may be grown, whereas, only p-type layers may be grown from Te-rich solution at atmospheric pressure.