LaAlO3 deep-UV photodetector is naturally solar-blind

The solar-blind properties of lanthanum aluminate (LaAlO₃), as well as its large bandgap energy of 5.6 eV, make it a good candidate material for deep-UV photodetectors. Researchers at the Chinese Academy of Sciences and the China University of Geosciences (both of Beijing, China) have, for the first time, created a single-crystal LaAlO₃ photodetector, basing it on a design with gold interdigitated electrodes and an effective detection area of 2 x 6 mm. At a 200 nm wavelength, its photocurrent response is 71.8 mA/W, while its quantum efficiency reaches 44.6%; in sunlight at room temperature, the detector has a noise current of 77 pA at 20 V bias.

The room-temperature spectral response of a LaAlO₃ detector with 5 µm electrode finger width at a 10 V bias highlights the device’s high sensitivity exclusively in the deep-UV range; the response shows a sharp long-wavelength cutoff at around 220 nm, as well as a 200 vs. 290 nm contrast ratio of more than two orders of magnitude. Because a commercial LaAlO₃ crystal is used, the photodetector is simple and inexpensive to fabricate. Contact Huibin Lu at [email protected].