Hexagonal YMnO3 films as promising ultraviolet photodetectors

Hexagonal rare-earth manganites (h-RMnO3, R = Sc, Y, Ho-Lu) exhibit intricate multiferroic properties and may be utilized for various technological applications ranging from non-volatile memories to solar cells and photo detectors. Here, we report the epitaxial growth of hexagonal YMnO3 (h-YMO) films with different thicknesses deposited on yttria-stabilized zirconia (YSZ) substrates and their photoresponses to ultraviolet (UV) light. The structural characterizations illustrate that all the films present high quality epitaxy with out-of-plane h-YMO (0001)//YSZ(111) and in-plane h-YMO[1230]//YSZ[110] relationship. Meanwhile, UV light driven photo responses of these as-prepared films based on the planar photodetector structure with transparent Al-doped ZnO (AZO) as top electrodes are explored. It is revealed that the photocurrent will first increase and then decrease with increasing film thickness. The highest photoconductivity gain is similar to 387.4 observed at +4 V bias for the device with 160 nm YMO film. These results provide a guideline for hexagonal rare-earth manganites to work for UV photodetector application.