Pressure dependence of effective dynamic charge in InxAl1−xAs ternary alloys

•Raman Scattering experiment was performed on InxAl1−xAs under high pressure.•Effective charge of InAs-like mode increases with increasing pressure for some x.•Most binary alloys show only decreasing effective charge with increasing pressure.•The competition between charge transfer and covalent character is responsible for this behavior.

Using Raman scattering data under high pressure, we show that InxAl1−xAs ternary alloys exhibit, depending on In molar fraction x, either decreasing or increasing effective dynamic charge for InAs-like mode with increasing pressure. The variation of the effective dynamic charge in ternary alloy is determined by two factors: (1) the charge transfer between two different vibrating pairs and (2) the tendency to reduce it under lattice contraction in binary case.