Liquid-phase epitaxy of In-doped PbTe for the application of mid-infrared semiconductor laser Original Research Article

Indium-doped PbTe epitaxial layers and pn homojunction diodes were grown on PbTe substrate using the temperature-difference method under controlled vapor pressure (TDM-CVP) liquid-phase epitaxy (LPE). The activation ratio of indium donor in the PbTe epitaxial layer was as high as 80%, and we achieved high electron concentrations up to nD=5×1019 cm−3. In view of the enhanced electron mobility, it is shown that the optimum Te vapor pressure for an In-doped PbTe epitaxial layer is about 2×10−5 Torr at 470 °C, which agrees well with the results for undoped and heavily Bi-doped PbTe epitaxial layers. In-doped n+-PbTe layer was successfully applied for the fabrication of broad contact pn junction lasers and excellent lasing emissions were achieved, characteristics as compared to Bi-doped and -undoped cladding layers. The threshold current for a broad area diode is 200 A/cm2 at 15 K and 2.7 kA/cm2 at 77 K.