PbSnTe double-heterostructure lasers and PbEuTe double-heterostructure lasers by hot-wall epitaxy

Abstract

Pb1−x Snx Te, double-heterostructure (DH) lasers and Pb1−x Eux Te DH lasers produced by hot-wall epitaxy have been studied. The growth temperature for both laser crystals is 300 °C. This is lower than the growth temperatures obtainable by molecular-beam epitaxy and liquid phase epitaxy. By investigating the I-V characteristics of Pb1−x Snx Te DH lasers with x values greater than 0.2, it was confirmed that the band structure of the p-n heterojunction is type 1′. A Pb1−x Snx Te1−y Sey layer, rather than a PbTe1−y Sey layer, should be used for the cladding layer of Pb1−x Snx Te DH lasers with x values greater than 0.2. One of the primary factors preventing an increase in the maximum operating temperature to 200 K is that the carrier density injected into the active layer is not sufficient for laser emissions over 200 K due to the p-n heterojunction of the type 1′ band structure. The band structure of the p-n heterojunction of Pb1−x Eux Te DH lasers is type 1. Therefore, the maximum operating temperatures of the Pb1−x Eux Te DH lasers are expected to be greater than those of Pb1−x Snx Te DH lasers. The maximum operating temperature of Pb1−x Eux Te DH lasers exceeded 200 K. The maximum operating temperature of the laser with a PbTe active layer was 170 K under CW operation and 243 K under pulsed operation. This temperature was nearly 50 K higher than the maximum pulsed operation temperature of Pb1−x Snx Te DH lasers.