Growth optimization of GaxIn1−xAsyP1−y/GaAs(0.98 μm) quantum wire heterostructures

Abstract

The strain-induced lateral-layer ordering technique has proven itself to be a viable method for creating quantum wires (QWRs) via molecular beam epitaxy. In an effort to achieve emission at the technologically important 0.98 μm wavelength, GaxIn1−xAsyP1−y QWRs formed on on-axis GaAs substrates using (GaP)m/(InAs)n short-period superlattices (SPS) are investigated. The growth parameters, such as the growth temperature, the source switching pause scheme, and the group-V source flow sequence are optimized to create QWRs with emission near 0.98 μm. For structures utilizing abrupt switching between constituent layers, it was determined that the optimal temperature at which to grow the (GaP)2.2/(InAs)1 SPS on GaAs was 480 °C. By introducing pause times and additional group-V source coverage to the growth scheme, the quality of the QWR heterostructure is markedly improved. The existence of a lateral composition modulation in the growth plane is evidenced by the low-energy emission (redshift) with respect to the bulk GaxIn1−xAsyP1−y, and the highly polarized nature of the photoluminescence (PL) spectra. Furthermore, the effects of the barrier material between QWR layers (in the growth direction) on the temperature stability of PL peak wavelengths near 0.98 μm were studied. The temperature induced wavelength shift depends on the barrier material, barrier thickness, and the composition of the SPS used in the QWR region. A minimum PL peak wavelength shift of about 200 Å between 77 and 300 K was observed in the GaxIn1−xAsyP1−y QWR system with Ga0.51In0.49P barriers.