The opportunities, successes and challenges for GaInNAsSb

Abstract

Dilute nitride GaInNAs and GaInNAsSb alloys grown on GaAs have quickly become excellent candidates for a variety of lower cost 1.2–1.6 μm lasers, optical amplifiers and high power Raman pump lasers that will be required for advanced high-speed communications systems. Two particularly critical devices are (1) vertical cavity surface emitting lasers (VCSELs) which must operate at high data rates (⩾10 Gbps), uncooled over a broad thermal operating range and (2) high-power (⩾500 mW) edge emitting lasers for Raman amplifier pumps. While progress has been both rapid and very promising, there remain some significant challenges. The major materials challenges include the limited solubility of N, a 2-D to 3-D growth transition with phase segregation, precise control over composition, strain and energy band offsets at heterointerfaces and elimination of non-radiative defects that are caused by some combination of N incorporation, low growth temperature and ion damage from the N plasma source. The addition of Sb significantly improves the epitaxial growth, maintaining 2-D growth over a broader range of growth temperature, larger In and N compositions, V/III ratio and significantly improves the optical properties at wavelengths longer than 1.3 μm. This paper describes progress in overcoming some of the material challenges, particularly low temperature GaInNAsSb growth, plasma source ion damage in solid source MBE and progress in realizing record setting long wavelength edge emitting lasers and the first monolithic VCSELs operating at 1.5 μm based on GaInNAsSb QWs grown on GaAs.