We report on the deposition of Ga2O3 using microwave irradiation technique on III-nitride epi-layers. We also report on the first demonstration of a Ga2O3 device a visible blind deep -UV detector -with GaN-based heterostructure as the substrate. The film deposited in the solution medium, at < 200 o C, using a metalorganic precursor, was nanocrystalline. XRD confirms that as deposited film when annealed at high temperature turns polycrystalline β−Ga2O3. SEM shows the as-deposited film to be uniform, with a surface roughness of 4-5 nm, as revealed by AFM. Interdigitated metal semiconductor metal (MSM) devices with Ni/Au contact exhibited peak spectral response at 230 nm and a good visible rejection ratio. This first demonstration of a deep-UV detector on β − Ga2O3/III-nitride stack is expected to open up new possibilities of functional and physical integration of β − Ga2O3 and GaN material families towards enabling next generation high-performance devices by exciting band and heterostructure engineering. a) Corresponding author email: piyushj@iisc.ac.in

This Perspective seeks to understand and assess why ultrawide bandgap (UWBG) semiconductor-based deep-UV photodetectors have not yet found any noticeable presence in real-world applications despite riding on more than two decades of extensive materials and devices’ research. Keeping the discussion confined to photodetectors based on epitaxial AlGaN and Ga2O3, a broad assessment of the device performance in terms of its various parameters is done vis-à-vis the dependence on the material quality. We introduce a new comprehensive figure of merit (CFOM) to benchmark photodetectors by accounting for their three most critical performance parameters, i.e., gain, noise, and bandwidth. We infer from CFOM that purely from the point of view of device performance, AlGaN detectors do not have any serious shortcoming that is holding them back from entering the market. We try to identify the gaps that exist in the research landscape of AlGaN and Ga2O3 solar-blind photodetectors and also argue that merely improving the material/structural quality and device performance would not help in making this technology transition from the academic realm. Instead of providing a review, this Perspective asks the hard question on whether UWBG solar-blind detectors will ever find real-world applications in a noticeable way and whether these devices will be ever used in space-borne platforms for deep-space imaging, for instance.

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In this report, we demonstrate direct epitaxial integration of β-Ga 2 O 3 on a (400) oriented silicon on insulator substrate toward deep-UV (DUV) optoelectronics. The 550 nm thick (400) epitaxial-β-Ga 2 O 3 films are deposited onto Si(100) using a two-step buffer and a two-step epilayer scheme. The epitaxial orientation relation between β-Ga 2 O 3 , MgO, and silicon( 100) is given by (400The presence of rotational variants is confirmed by Xray diffraction and transmission electron microscopy. Epitaxy was found to be mediated through a MgGa 2 O 4 layer formed at the β-Ga 2 O 3 /MgO interface under oxygen-deficient conditions during pulsed layer deposition. The ω-scan symmetric and asymmetric full width at half-maximum values of β-Ga 2 O 3 are 2.41 and 2.39°, respectively. Photodetectors realized in a conventional metal− semiconductor−metal geometry exhibit a maximum responsivity of 11.8 A/W at 246 nm at 40 V with a photo to dark current ratio of 2.5 × 10 2 and a UV-to-visible rejection ratio > 10 3 . The detectors do not exhibit any persistent photoconductivity as is evident from the rise and fall times of 0.54 and 0.32 s, respectively. Such a monolithic integration of β-Ga 2 O 3 on Si(100) opens up opportunities for the development of integrated DUV focal plane arrays on a SoC chip.