Comparison of GaNAsSb and GaNAs as quantum-well barriers for GaInNAsSb optoelectronic devices operating at 1.3–1.55μm

Abstract

Ga N As Sb ∕ Ga As quantum wells were grown by solid-source molecular-beam epitaxy utilizing a radio-frequency nitrogen plasma source. The GaNAsSb layers, originally the quantum well barrier materials for GaInNAs(Sb) devices, were studied for their general growth characteristics as well as their structural and optical properties, which give an indication of its quality as a quantum well barrier material. Reflection high-energy electron diffraction, high-resolution x-ray diffraction, secondary-ion mass spectroscopy, and photoluminescence (PL) measurements were used to study those properties. The growth parameters including arsenic overpressure and substrate temperature were changed systematically to determine the properties during deposition and to optimize these conditions. It was found that the addition of antimony to GaNAs did not improve the material as it did for GaInNAs. PL measurements indicated a decreasing optical quality with an increasing substrate temperature and no change with the arsenic overpressure. In addition, the addition of antimony had eliminated the lattice-strain compensation provided by the GaNAs barriers. Using GaNAs rather than GaNAsSb barriers in the GaInNAs(Sb) devices was found to be advantageous and has dramatically improved the performance of long-wavelength GaAs-based lasers.