A unique metal–semiconductor–metal (MSM) photodetector has been fabricated using Sn incorporation in Ga ₂ O ₃ forming Sn _x Ga _{1- x} O nanostructures (Ns) with platinum (Pt) metal as contacts. The mixed nanostructures (MNs) has been attributed to an increment in the detection range of UV (254–302 nm) with ultra-low dark current, hence a potential device in the field of long range deep-UV detector. Sn _x Ga _{1- x} O Ns are deposited on c-plane sapphire using low-pressure chemical vapour deposition. From the x-ray diffraction (XRD) results, existence of both Sn _x Ga _{1- x} O and tetragonal SnO ₂ MNs are confirmed. The XRD peak shifts in Sn _x Ga _{1- x} O are attributed to the integration of Sn with Ga forming a Sn _x Ga _{1- x} O alloy with x to be ∼7.3% determined from the Vegard’s law. The field effect scanning eletron microscope images show the thick diameter wire-shaped nanostructures. The absorption spectra show a trace of two absorption edges corresponding to both Sn _x Ga _{1- x} O and SnO ₂ Ns. Photo to dark current ratio (PDCR) of the fabricated photodetector is large (10 ³ ) at 2 V bias with fast fall time of 0.18 s. The detector reveals self-powered behaviour also with PDCR >10 ⁴ at 0 V bias. The dark current is ultra-low (13 pA at 5 V) due to high barrier height of Pt and the UV detection range has been extended from 254–302 nm with a very small drop in PDCR owing to incorporation of Sn.

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.

Reduction of high dark current has been a challenge for high responsivity photodetector (PD). In this context, the present article demonstrates an ultralow dark current of Ga₂O₃-based deep ultraviolet (UV)-photodetectors (UV-PDs) with enhanced photoresponses by tailoring a p/n heterojunction. An n-Ga₂O₃/p-CuO quasi-heterostructure-based deep UV-PDs has been fabricated on a sapphire (0001) substrate using an inexpensive electrospraying technique. After Ga₂O₃ deposition, platinum (Pt) electrodes (~50 nm) are fabricated as a metal-semiconductor-metal (MSM) device using sputtering. The device exhibits a very low dark current in the order of few fA (6.94x10⁻¹⁴ A) at 5 V because of the enhanced depletion width at p/n heterojunction and Pt/Ga₂O₃ metal-semiconductor contacts, which provides a narrow path for free carriers to travel from one metal contact to other under dark condition. The depletion layers get thinner due to the absorption of UV-photons in the UV-illumination condition. Hence, the photogenerated carriers get a wider channel to get collected at Pt-electrodes. Thus, in addition to ultralow dark current, the device exhibits an extraordinary photodetection characteristics, such as a high responsivity (~6.33 x 10³ AW⁻¹), remarkable photo-to-dark current ratio (~2.99 x 10⁶), very high detectivity (~4.44 x 10¹⁴ mHz0.5W⁻¹), and exceptional external quantum efficiency of ~3.1 x 10⁶% at 5 V.

This article proposes a new junction barrier Schottky diode (JBSD) design based on P-GaN/N-Ga ₂ O ₃ heterojunction with faster switching characteristics and higher breakdown ability than the traditional two-terminal power switches. Calibrated models have been used for technology computer-aided design (TCAD) simulations of the proposed JBSD after a comprehensive review of various physical models and model parameters in the present literature. Analysis in terms of static and transient behavior for a varying proportion of PN area to the Schottky contact area (PN:SBD ratio) was looked upon for the JBSD. With the increase of PN:SBD ratio, the reverse voltage handling capability increased as expected, but the reverse recovery time and maximum reverse recovery current decreased. This might be counterintuitive initially, as with an increase in PN:SBD ratio, the PN behavior would dominate over SBD, and slower transient behavior is expected. However, due to redistribution of electric field and the reduction in depletion capacitance across the JBSD with increase in PN:SBD ratio, JBSD with PN:SBD ratio of 8 gives us a breakdown at 1890 V and a switching time of 9.72 ns. Furthermore, a comparison of the transient response with state-of-the-art SiC Schottky diode reveals the efficiency of the proposed structure in terms of reverse recovery parameters to be significantly better, translating to 7.4 times lower power losses at higher frequencies. Overall, the design and analysis presented here suggest the promising potential of P-GaN/N-Ga ₂ O ₃ vertical devices for high-voltage and fast switching applications.

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.