Tunable band gap in epitaxial ferroelectric Ho(Mn,Ga)O3 films

Ferroelectrics have recently attracted attention as a new class of materials for use in optical and photovoltaic devices. We studied the electronic properties in epitaxially stabilized ferroelectric hexagonal Ho(Mn1- xGax)O3 (x = 0, 0.33, 0.67, and 1) thin films. Our films exhibited systematic changes in electronic structures, such as bandgap and optical transitions, according to the Ga concentration. In particular, the bandgap increased systematically from 1.4 to 3.2 eV, including the visible light region, with increasing Ga concentration from x = 0 to 1. These systematic changes, attributed to lattice parameter variations in epitaxial Ho(Mn1- xGax)O3 films, should prove useful for the design of optoelectronic devices based on ferroelectrics. © 2016 Author(s)1111sciescopu