MOVPE growth of InAlGaP-based visible vertical-cavity surface-emitting lasers

Abstract

Materials growth issues for visible vertical-cavity surface-emitting lasers have been addressed in detail. For high optical efficiency in the laser cavity, the optical properties of In 0.48(Al y Ga 1- y ) 0.52P quarternary alloys lattice-matched to GaAs were optimized as a function of MOVPE growth parameters including substrate temperature and misorientation. The narrowest photoluminescent linewidths yet reported for all of the direct bandgap In(Al y Ga 1- y )P alloys (0⩽ y⩽0.5) were observed, including 4.2 meV for InGaP. The growth and optical properties of strained quantum well structures were then investigated for use in the laser active region. Structures with a broad range of well and barrier compositions and thicknesses were prepared, and characterized using low-temperature photoluminescence. Based upon this work, high-optical quality strained and unstrained multiple-quantum-well heterostructures were grown for use in the 640–670 nm wavelength range. Epitaxial multilayer dielectric mirror stacks reflecting at visible (620–700 nm) wavelengths were fabricated from the Al 0.5Ga 0.5As/AlAs and InGaP/InAlP systems, and for both types of mirrors excellent reflectivity characteristics were observed. Visible VCSEL structures were grown for photopumping experiments, and the structures exhibited low threshold powers. Wavelength of operation of these structures was in the range 632–661nm.