Heavily silicon doped InGaAlAs InP epilayers grown by molecular beam epitaxy

Abstract

Silicon doped n-type In0.53Ga0.08Al0.39As epilayers lattice matched to InP substrate are grown by molecular beam epitaxy. The epilayers grown are reproducible and of excellent crystal quality as indicated by the mismatch figure of less than 3.0 × 10-4 and half widths of 25-30 arcsec in the diffraction peaks. Photoluminescence at room temperature and 5 K showed luminescence peaks at 918 and 880 nm with half widths of 70 and 12 meV respectively. Doping levels as high as 2.0 × 1019 cm-3 have been achieved under optimum growth conditions and were observed to saturate at this value. However, no significant enhancement in the mobility could be observed at 77 K compared to the room temperature values. This is associated with the alloy scattering due to the three group III elements in the material as the dominant scattering mechanism. A theoretical estimate of the mobility limit based on the alloy scattering potential due to the energy band gap difference, suggests good matching with the experimentally observed values. © 1995.