Energy Level Alignments in Strained-Layer GaInP/AlGaInP Laser Diodes: Model Solid Theory Analysis of Pressure-Photoluminescence Experiments

摘要

We report high-pressure photoluminescence (PL) experiments on GaInP/AlGaInP laser structures and a comprehensive interpretation of the results via calculations based on the Model Solid Theory (MST) of Van de Walle et al. [1, 2]. This methodology allows an accurate description of the band structure and band offsets in complex heterostructures over a wide range of sample compositions and applied pressures. Measurements are performed on Ga_(0.4)In_(0.6)P/(Al_(0.6)Ga_(0.4))_(0.5)In_(0.5)P (nominal compositions) double heterojunction samples having active layers of either 125 or 30 A. The pressure data determine a reliable set of deformation potentials for the three constituent binary compounds in this system, InP, AlP and GaP. Using these deformation potentials and a realistic equation of state, the MST calculation gives a reasonable representation of the observed PL spectra over the full presure range (0 to 5 GPa) studied. The conduction band offset triangle open E_c, valence band offset triangle open E_v, and the bulk bandgap energies are computed in this materials system for a wide variety of conditions. At ambient pressure we find triangle open E_c : triangle open E_v approx= 70 : 30, in accord with the consensus value of the band-offset ration in similar heterostructures. However, our calculations predict band-offset variations with both composition and applied pressure that are non-negligible.