Movpe growth and characterization of dilute III-(III)-V-nitride semiconductor : ingapn on gaas

Abstract

In the dissertation, the characteristics of InGaPN/GaAs related to the using as the absorber layer in solar cell were analyzed. In order to verify the band alignment, the InGaPN/GaAs and GaAs/InGaPN quantum wells (QWs) with high structural quality were grown on (001) GaAs substrates by metalorganic vapor phase epitaxy (MOVPE). The results from 10K photoluminescence (PL) of QWs show the extra peaks in infrared energy range. The extra peak of GaAs/InGaPN QW survives for the temperature up to 240K while The extra peak of the InGaPN/GaAs QW is quenched at the temperature about 120K. This situation suggested that both QWs are the type-II quantum structures. The valence and conduction band offsets are approximated to be 450 and 160 meV, respectively. In order to investigate the energy gap of InGaPN and its variation with temperature, the InGaPN layers with various N concentrations were coherently grown on (001) GaAs substrate. With increasing N, the results of PL and photoreflectance (PR) show that the energy gap is decreased. The temperature dependent PL together with fitting show that the temperature dependence of the bandgap energies of InGaPN layers becomes significantly weak with increasing N content. The fitting parameters show the values shift toward the III-nitride (i.e. GaN and InN) characteristic with increasing N. the Raman scattering results in the range of 400 – 900 cm-1 show the GaN-like characteristic. This suggests that the Ga-N bonds make a larger contribution than In-N bonds in InGaPN samples. The less dependence of bandgap on temperature property might be mostly contributed by Ga-N bonds.