High pressure induced phase transition in sulfur doped indium phosphide: An angular-dispersive X-ray diffraction and Raman study

The high pressure induced phase transitions in sulfur doped indium phosphide (InP:S) at ambient temperature has been investigated using angular-dispersive X-ray diffraction (ADXRD) and Raman scattering under high pressure up to around 44.6 and 37.4 GPa, respectively. In situ ADXRD measurements found that the transition of InP:S to a rock-salt phase began at 10.4 GPa and completed at 13.3 GPa with a 15.7% volume decrease. Another transition to the orthorhombic structure with space group Cmcm (the Cmcm phase) was found to occur at 35.8 GPa with a 4.1% volume decrease. The fitting of volume compression data to the third-order Birch-Murnaghan equation of state yielded that the zero-pressure isothermal bulk moduli (B₀) and the first-pressure derivatives (B₀^′) were 74 GPa and 3.9 for the zinc-blende phase, respectively. The rock-salt to Cmcm phase transition pressure increases relative to that of undoped InP of 32 GPa, which may be attributable to the increase of the ionicity of InP:S by S doping favorable to the ionic rock salt structure. In situ Raman measurements have similar findings.