We report on a high performance Pt/n⁻Ga₂O₃/n⁺Ga₂O₃ solar blind Schottky photodiode that has been grown by metalorganic chemical vapor deposition. The active area of the photodiode was fabricated using ∼30 Å thick semi-transparent Pt that has up to 90% transparency to UV radiation with wavelengths < 260 nm. The fabricated photodiode exhibited Schottky characteristics with a turn-on voltage of ∼1 V and a rectification ratio of ∼10⁸ at ±2 V and showed deep UV solar blind detection at 0 V. The Schottky photodiode exhibited good device characteristics such as an ideality factor of 1.23 and a breakdown voltage of ∼110 V. The spectral response showed a maximum absolute responsivity of 0.16 A/W at 222 nm at zero bias corresponding to an external quantum efficiency of ∼87.5%. The cutoff wavelength and the out of band rejection ratio of the devices were ∼260 nm and ∼10⁴, respectively, showing a true solar blind operation with an excellent selectivity. The time response is in the millisecond range and has no long-time decay component which is common in photoconductive wide bandgap devices.

The existence of a correlation between current collapse and off-state reverse-bias leakage current in heteroepitaxially grown AlGaN/GaN high-electron-mobility transistors is investigated from the perspective of conductive threading dislocations. Collapsed current response (recoverable) to synchronized gate-drain voltage pulses is found to be governed by the epilayer's dislocation density, and also by the off-state quiescent bias scheme. Furthermore, magnitudes of reverse-gate leakages apart from being dislocation density dependent are found to have distinctive temperature-bias characteristics. Based on the trapping spatiality along with field and temperature dependence of the respective leakage currents; an emission mechanism is postulated involving donor-like surface states and dislocation induced deep levels. It is inferred that dislocations can indeed be responsible for the current collapse that has been long assumed to be caused by the surface states.

The work presents a comparative study on the effects of In incorporation in the channel layer of AlGaN/GaN type-II heterostructures grown on c-plane sapphire by Plasma Assisted Molecular Beam Epitaxy. The structural characterizations of these samples were performed by High-Resolution X-Ray Diffraction (HRXRD), X-ray Reflectivity (XRR), Field Emission Scanning Electron Microscopy, and High Resolution Transmission Electron Microscopy. The two-dimensional electron gas in the AlGaN/GaN and AlGaN/InGaN interface was analyzed by electrochemical capacitance voltage and compared with theoretical results based on self-consistent solution of Schördinger–Poisson equations. The carrier profile shows enhanced confinement in InGaN channel (1.4393 × 10¹³ cm⁻² compared to 1.096 × 10¹³ cm⁻² in GaN). On the basis of HRXRD measurements, the stress-strain of the layers was examined. The c- and a-lattice parameters of the epilayers as well as in-plane and out-of plane strains were determined from the ω-2θ for symmetric scan and ω-Xθ (X represents the coupling coefficient) for asymmetric scan. Strain, tilt, and correlation lengths were calculated from Williamson–Hall plots, whereas stress was examined from modified plot of the same data assuming Uniform Stress Deformation Model. Moreover, the twist angle was measured from skew symmetric scan of (102), (103), and (105) plane along with (002) symmetric plane. The composition and strain/relaxation state of the epilayers were observed in detail by reciprocal space mapping (RSM). The symmetric (002) triple axis RSM and asymmetric (105 and 114) double axis RSM of grazing incidence and exit geometry were carried out on each sample. The defect density was measured from HRXRD curves of skew symmetric (002) and (102) reflection plane. The Al and In mole fraction and strain states of the layers were calculated by fitting the experimental curves with computer simulations and compared with theoretical findings based on elastic theory. The thicknesses of the layers and roughness of the interfaces were measured from simulation of the nominal structure by fitting with XRR experimental curves. The HRXRD measured thicknesses of the layers were further confirmed by cross sectional electron micrographs.

The authors report on high spectral responsivity (SnxGa1 − x)2O3 Schottky UV photodetectors grown by plasma-assisted molecular beam epitaxy on β-Ga2O3 substrates. Schottky devices exhibited peak responsivities ranging from 49 to 194 A/W, with peak responsivity and wavelength position increasing systematically for higher Sn concentration from x = 0.01 to 0.18. Dark currents for the devices ranged from <1 nA to 3 μA with rise and fall times in the 0.21–3 s time range, with slower response times likely due to photoconductive gain caused by trapped holes. Incorporation of up to 18% Sn into the tin gallium oxide (TGO) devices resulted in a redshift in the peak responsivity position, ranging from 5.19 to 4.86 eV, demonstrating tunability within the UV-C spectral region through Sn concentration adjustment. The authors believe this to be the highest reported responsivity for a planar Ga2O3-based Schottky photodetector to date, suggesting that TGO based UV-C Schottky detectors are an attractive approach toward deep-UV sensing applications.