Pressure-induced variation of effective dynamic charge in InP1−xAsx alloys due to charge transfer within cation sublattice

From the measurements of Raman spectra of ternary InP1−xAsx (x=0.4, 0.6, and 0.8) under high pressure, the pressure-dependence of the ionicity was found to be strongly affected by the As mole fraction x. In particular, for x=0.6 and 0.8 ternary alloys, the effective dynamic charge of InP-like mode strictly increases with pressure, in sharp contrast to the corresponding behavior satisfied by the majority of III–V and II–VI binary compounds including InP. This can be understood by the charge transfer from As to P in the cation sublattice when the ternary alloys are under pressure.