Insights on hexagonal TbMnO3 for optoelectronic applications: From powders to thin films

Abstract In this work, we first report on the fabrication of TbMnO3 (TMO) powders and doping with In, Lu, Gd, Sm, Nd, Y. In and Nd atoms were found to significantly reduce the cell size while preserving an orthorhombic structure. Conversely, we show that hexagonal h-TMO, indium doped TMO (h-In-TMO), yttrium doped TMO (h-Y-TMO), and YMnO3 (h-YMO) can be obtained epitaxially using pulsed laser deposition (PLD) on Pt (111)//Al2O3 (0001). The evolution of the optical properties was measured for the PLD films and a direct bandgap of 1.5–1.6 eV was found for h-TMO and doped h-TMO films. The h-TMO, h-In-TMO and h-Y-TMO showed no sign of ferroelectricity at room temperature as opposed to h-YMO. No short-circuit current in solar cell configuration was found under 1 sun illumination. However a photovoltaic behavior was observed by surface photovoltage for the h-Y-TMO and h-YMO, indicating that Y incorporation in h-TMO is helpful for the photovoltaic properties.