Orthorhombic undoped κ-Ga2O3 epitaxial thin films for sensitive, fast, and stable direct X-ray detectors

Photoelectronic properties of orthorhombic undoped kappa-Ga2O3 epitaxial thin films, grown on sapphire substrates by metal-organic vapour phase epitaxy, were evaluated under X-ray irradiation (CuK alpha line, 8.05 keV) for the first time. Photoresponse linearity at low dose-rates (varying in the 10-200 mu Gy s(-1) range), and excellent detection sensitivity (up to 342.3 mu C Gy(-1) cm(-3)), were demonstrated even at very low applied electric fields (down to 0.001 V mu m(-1)). Photocurrent rise time was evaluated to be <0.5 s, and signal stability was assessed for exposure times up to 2 h, highlighting no degradation of the performance. These encouraging results, mostly due to the extremely low dark current measured (in the pA range), suggest that orthorhombic undoped kappa-Ga2O3 is a promising material for the fabrication of sensitive and stable large-area X-ray detectors with minimum power consumption.

Automated summary

The photoelectronic properties of orthorhombic undoped kappa-Ga2O3 epitaxial thin films grown on sapphire substrates using metal-organic vapor phase epitaxy were evaluated for the first time. The films demonstrated linear photoresponse at low dose rates, excellent detection sensitivity, low dark current, and stability, making them promising for the fabrication of large-area X-ray detectors with minimum power consumption.