Ferroelectric and optical absorption properties of a new trigonal structure In_0.5Sc_0.5P: first-principles calculations

It is very important to obtain a new FE-PV material with a narrow bandgap and a large ferroelectric polarization to induce the development of FE-PV materials. On the basis of InP, a high visible light absorption material, we calculate the wurtzite structure In_1 − xSc_xP in this work. Interestingly, it was found that a new ferroelectric phase t-In_0.5Sc_0.5P (a trigonal structure with space groups P3m1), which is the transition phase from the ferroelectric phase w-In_0.5Sc_0.5P to the paraelectric phase In_0.5Sc_0.5P (p-In_0.5Sc_0.5P), has a lower energy than w-In_0.5Sc_0.5P. The polarization switching barrier of t-In_0.5Sc_0.5P decreased remarkably from 0.95 eV of w-InP to 0.093 eV due to the introduction of Sc. The ferroelectric polarization of t-In_0.5Sc_0.5P is 21.2 µC/cm². t-In_0.5Sc_0.5P has excellent visible light absorption properties compared to those of w-InP and Si in the long wavelength range. This work shows that the III-V doping groups are potential FE-PV materials.