Analysis of band anticrossing in InGaPN alloys grown on GaAs substrates

The band anticrossing (BAC) model is introduced to describe the influence of the incorporated nitrogen on the band structure of dilute nitrides. An isolated N introduces highly localized states in these nitrides, which interact with the extended conduction-band states of the host semiconductor. The interaction splits the conduction band into an upper and a lower subband. There are reports of the band-gap reduction in In-GaPN, but no experimental observations of the upper subband have been reported. In this work, temperature-dependent photoreflectance (PR) and photoluminescence (PL) spectra are employed to examine the band structure of InGaPN/GaAs heterostructures. Besides the band gap, the upper subband predicted by the BAC model is observed in the PR spectra. By eliminating the contributions of the strain and ordering effects in InGaPN, and assigning the localized state energy EN introduced by an isolated N to be 2.04 eV at 293 K, the interaction potential is determined as 1.449±0.170 eV. With N incorporation, the PL peak energy exhibits a particular behavior with temperature, which is not observed in the PR spectra. This is attributed to carrier localization at low temperatures occurring in N-diluted semiconductors. Additionally, the temperature dependence of the band gap is described by the BAC model incorporating two different EN levels, either constant or temperature-dependent. In our hands, the assumption of the temperature-dependent EN level results in a better fit with the experimental data.