High-performance 405-nm photodetector based on the defect-induced absorption in the rutile GeO2 film

Abstract

Owing to the existence of numerous defect states in the bandgap, ultra-wide bandgap oxide semiconductors (UBOSs) have been considered as promising candidates for broadband photodetections. However, the persistent photoconductivity (PPC) effect induced by the capture of minority carriers in the relaxation process results in a very slow recovery rate, which hampers the development of UBOS based broadband photodetectors. In this work, the high-quality rutile structure GeO₂ (r-GeO₂) film with an ultra-wide bandgap energy of 4.67 eV has been deposited on the quartz substrate using magnetron sputtering epitaxy technique followed by the thermal annealing process. Taking advantage of the oxygen defect absorption of the r-GeO₂ film, a 405 nm photodetector has been achieved for the first time, which exhibits the photoresponsivity of 6.92 × 10⁻³ A/W and the detection rate of 3.06 × 10⁹ Jones, respectively, under the optical power density of 0.03 mW/cm². Moreover, a fast decay time of 0.18 s measured at a bias voltage of 30 V has been confirmed for the r-GeO₂-based photodetector without the PPC effect due to the recombination of non-equilibrium carriers mainly induced by the defect states. The proposed r-GeO₂ based broadband photodetectors enjoy high-performance, cost-effectiveness, convenience, and facile operation, providing a potential solution for broadband photodetection applications.