Elevated temperature performance of Si-implanted solar-blind b-Ga2O3 photodetectors.

The temperature dependent photoresponse of planar photodetectors fabricated on β-Ga₂O₃ films grown on Al₂O₃ by metalorganic chemical vapor deposition to 254 nm wavelength, and blindnessto 365 nm light, are reported over the range of 25-350 °C. Ohmic contacts were formed by Siimplantationand annealing at 900 °C, followed by deposition of Ti/Au metallization. The photocurrentinduced by 254 nm illumination increased monotonically with temperature, from 2.5 ~10^-7A at 25°C to ~2.2 ~10^-6 A at 350 °C at a fixed 254 nm light intensity of 760 μW/cm². The photosensitivitydecreases at high temperatures in many photoconductors (thermal quenching), in sharpcontrast to the photosensitivity increase with high temperatures in this study. This is ascribed to thepresence of states in the gap of Ga²O³, whose presence was proven by exposure to below band-gapenergy. In this case, the current still increased due to the presence of defect levels in the band gapand the generation of photocurrent is due to a transition between the valence or conduction bandand impurity or defect levels within the band gap. The temperature dependent photo-to-dark currentratio for this wavelength was 328 at room temperature and decreased to ~9 at 350 °C. The responsivityincreased from 5 to 36 A/W over this temperature range, with corresponding external quantumefficiencies of 2.5 ~ 10³% at 25°C and 1.75 ~ 104% at 350 °C. Similarly large numbersreported for Ga₂O₃ photodetectors have previously been ascribed to carrier multiplication effects. [ABSTRACT FROM AUTHOR]