Narrow-band photodetection by heterolattice electronic transitions in TiO${}_2$ glass embedded with nanocrystals

Abstract

In this letter, we propose that the narrowband photodetection can be realized in the skin layer of semiconductors with the spatially separated photo-excited carriers from the nanoscale heterolattice electronic transitions (NanoHLETs). The NanoHLET photodetection is demonstrated by measuring the photoconductive responses of the $\sim$ 1 $\mu$m thick films of TiO${}_2$ glass embedded with rutile and anatase TiO${}_2$ nanocrystals. As containing only rutile nanocrystals, the TiO${}_2$ glass film presents the responsivity curve with only one sharp peak centered at 423.0 nm with a full-width-at-half-maximum (FWHM) of 13.7 nm. This NanoHLET mechanism may open a new way in making ultra-small narrow-band photodetectors matching the current nanoscale electronic technology.