Preparation and Optical Properties of InAs1−xPx Alloys

Homogeneous polycrystalline InAs1−xPx alloys have been prepared by a halogen vapor-transport closed-tube technique over the entire range of composition. Electroreflectance measurements were made at room temperature by the electrolyte method which showed that the E1 and E1+Δ1 transition energies vary in a concave upwards manner, while the E0′, E2, and E2+δ transition energies vary linearly with composition. Wavelength-modulated reflectance measurements on semiconducting alloys above the fundamental edge are reported for the first time. These data, taken at room and liquid-nitrogen temperatures, confirm the interpretation placed on the variation of the electroreflectance E1 peaks. The E1 spin-orbit splitting (Δ1) remains almost constant in energy as x is increased from InAs and then falls rapidly to the InP value. A similar shape is obtained for Δ1 from a k·p calculation for the alloy band structure, which shows that a movement of the transitions in k space is probably responsible for this behavior.