Growth of compressively strained GaxIn1−xAsyP1−y quantum wells for 690–730 nm laser emission

Abstract

AlxGa1−xAs-based lasers are typically used for emission wavelengths of 730 nm and above, e.g. using GaAsyP1−y quantum wells (QW), while lasers emitting below 700 nm rely on (AlxGa1−x)0.5In0.5P in combination with GaxIn1−xP quantum wells. The 690 nm to 730 nm spectral range could basically be addressed from both ends, but this is practically limited by the tensile (GaAsyP1−y) and compressive (GaxIn1−xP) strains necessary to reach this spectral range. In this work we report on our efforts in growing GaxIn1−xAsyP1−y for emission around 700 nm. As this quaternary material is prone to phase separation, we first studied the growth of lattice matched bulk layers. We show that phase separation is kinetically triggered and can be avoided by staying below a critical thickness. Compressively strained GaxIn1−xAsyP1−y QWs can be grown if strain is kept below a critical value. The quantum well strain, which drives kinetic phase separation, is adjusted by a combination of X-ray diffraction and electroluminescence evaluated by modelling of the transition energies. Finally, we present LIV characteristics of uncoated edge-emitting broad area lasers (100 × 1000 µm2) reaching output powers up to P = 900mW at I = 2A for emission wavelengths ranging from 690 to 726 nm.