Studies of band alignment and two-dimensional electron gas in InGaPN/GaAs heterostructures

Room-temperature photoreflectance (PR) and photoluminescence (PL) spectra are measured for a f series of In _0.54Ga _0.46P _1-yN _y/GaAs heterostructures grown on GaAs (100) substrate. Redshifts of the PR and PL peaks indicate that the band gap of In _0.54Ga _0.46P _1-yN _y is dramatically reduced as nitrogen is incorporated. The emergence of additional peaks in PR spectra as nitrogen is incorporated indicates that the band alignment switches from type I to type II, due to the lowering of the conduction band, thus forming a two-dimensional electron gas (2DEG) in the interface region between In _0.54Ga _0.46P _1-yN _y, and GaAs. The band gap energy and transition energies between the confined levels in the 2DEG are determined for samples with various nitrogen concentrations v. The number of confined levels in the 2DEG is found to increase with y; the composition-dependent bowing parameter is determined.