PHOTOLUMINESCENCE AND BAND OFFSETS OF ALINAS/INP

We report the temperature dependence of Al0.46In0.54As photoluminescence (PL) transition energies and Al0.46In0.54As/InP interface staggered line-up luminescence (SLL) energy. The S shape appearing from 4 to 90 K on the energy versus temperature curves of these PL energies is due to extrinsic recombinations. In particular, the S shape of the SLL energy curve versus temperature is probably due to acceptor impurities localized in AllnAs, at the interface (on-edge impurities). The binding energy of on-edge impurities is lower than its value in the bulk material. This explains why the S shape is less pronounced on the SLL than on the AllnAs PL curve. The band offsets were determined by solving the Schrodinger-Poisson equation system with a self-consistent calculation program. At 4.5 K, the conduction and valence band offsets of the Al0.46In0.54As/InP interface were respectively 0.384 eV and 0.295 eV. This is in agreement with the already reported value of 410 meV for the conduction band offset of the lattice-matched Al0.48In0.52As/InP heterostructure. The temperature dependence of the conduction and valence band offsets is shown to be important: respectively 35 meV and 23 meV between 4.5 and 300 K. The Van Vechten-Malloy model (following a thermodynamic approach) for the temperature dependence of the band offsets is compared with our results. The comparison shows only a qualitative agreement.