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We report on record high zero-bias external quantum efficiency (EQE) of 92% for back-illuminated Al0.40Ga0.60N p-i-n ultra-violet (UV) photodetectors on sapphire. The zero-bias responsivity measured 211 mA/W at 289 nm, which is the highest value reported for solar-blind, p-i-n detectors realized over any epitaxial wide band-gap semiconductor. This is also the first report for a p-i-n detector, where a polarization-graded Mg-doped AlGaN layer is utilized as the p-contact layer. The devices exhibited a ten-orders of magnitude rectification, a low reverse leakage current density of 1 nA/cm2 at 10 V, a high $\text{R}_{{0}}\text{A}$ product of $1.3\times 10^{{11}} \Omega $ .cm2 and supported fields exceeding 5 MV/cm. The light-to-dark current ratio and the UV-to-visible rejection ratio for the detectors exceeded six-orders of magnitude and the thermal noise limited detectivity (D*) measured $6.1\times 10^{{14}}$ cmHz1/2W−1. The state-of-the-art performance parameters can be attributed to a high crystalline quality absorbing AlGaN epi-layer resulting from the use of an AlN/AlGaN superlattice buffer and an improved p-contact via polarization grading.

In this letter, we demonstrate $1 \times 8$ linear metal–semiconductor–metal arrays of UV-C photodetectors based on optical-float-zone grown bulk (100)-oriented $\beta $ -Ga2O3. The as-grown polished bulk samples exhibited an RMS roughness of 1.4 nm and the full-width at half-maxima of 0.19°. The average peak responsivity (257 nm), dark current, photo-to-dark current ratio, and UV-to-visible rejection ratio of the devices in the array were measured to be 4 AW $^{-1}$ , 0.23 nA, $\sim 10^{2}$ , and $\sim 10^{3}$ , respectively, at a bias of 40 V. The uniformity as well as the variability of the detector parameters across the devices in the array was investigated before and after wire bonding.

We report on the demonstration of visible/near-IR high-performance photodetector based on exfoliated $\beta $ -Indium selenide (In2Se3) on sapphire with a clear signature of band edge in spectral responsivity at a wavelength of ~850–900 nm. Room temperature photoluminescence (PL) measurements also indicated a peak at ~900 nm confirming the band-edge. Devices with inter-digitated metal-semiconductor-metal (MSM) geometry exhibited a responsivity of 3.8 A/W (normalized to device area). A low dark current of 0.80 nA and a photo to dark current ratio of ~52 were measured when illuminated with 650 nm A specific detectivity of $1 \times 10^{10}$ cm Hz $^{0.5}\,\,\text{W}^{-1}$ at 650 nm and $6 \times 10^{8}$ cm Hz $^{0.5}\,\,\text{W}^{-1}$ at the band-edge of 900 nm were estimated. These results indicate the promise of $\beta $ -(In2Se3) for visible/near-IR detector applications.

In this letter, we demonstrate high-performance vertical solar-blind Schottky photodetectors on MBE-grown homoepitaxial (010)-oriented $\beta $ -Ga2O3 films. The structure, consisting of (100 nm) $\beta $ -Ga2O3/(60 nm) $\text{n}^{++} \beta $ -Ga2O3, was grown on a Fe-doped insulating (010) $\beta $ -Ga2O3 substrate. Ni/Au and indium were used as the Schottky and Ohmic contacts, respectively. The devices exhibited a rectification ratio of ~107 with turn-on voltage ~1 V and an ideality factor of 1.31. The extracted Schottky barrier height was 1.4 eV. The photodetectors showed low dark current of 0.3 nA at 5 V with a photo-to-dark current ratio of ~102 at 0 V. The devices exhibited a zero-bias responsivity of 4 mA/W at 254 nm corresponding to an external quantum efficiency ~3 %, with a UV-to-visible rejection ratio >103, showing true solar-blind operation. The transient response of the devices indicated rise/fall times of ~100 ms. Temperature-dependent current–voltage characteristics agree with the thermionic emission model.