Optical Studies Of GaAsSbN Alloys and Their Quantum Well Heterostructures

Abstract

Abstract : In this work, the growth and characterization of GaAsSbN quantum wells (QWs) grown in an elemental solid source molecular beam epitaxy (MBE) system with a RF plasma nitrogen source is presented. A systematic study has been carried out to determine the influence of various growth conditions such as the source shutter opening sequence, substrate temperature, various nitrogen (N) pressures and annealing in various ambient on the optical and structural properties of the QWs. N and Sb incorporations were found to depend strongly upon both the substrate temperature and source shutter opening sequence. The substrate temperature in the range of 430-470 deg C was found to be Optimum. The presence of Pendullusong and high frequency fringes due to the cap layer were observed in high-resolution x-ray diffraction (HRXRD) spectra of QWs, for N composition variation up to 2.3%, attesting to the excellent structural quality of the grown layers and interfaces. With increase in N concentration up to 0.7% the energy gap decreases at a rate of 270meV/% change in N, while with further increase in N concentration the change in PL peak energy reduces to 30meV/% change in N. Narrow PL FWHM of 20 meV at PL peak energy of 0,82 eV at 4K has been achieved on annealed samples. The PL temperature dependence studies carried out on these samples indicate evidence of inverted s-shaped behavior in the low temperature regime, being more pronounced in samples annealed in a N ambient. The samples annealed in Situ under an As overpressure exhibit less carrier localization, which is attributed to a reduction in the nonradiative recombination centers.