Gate-controllable 213 nm photo-responsivity in GeO2/SiO2/p-Si three-terminal solar-blind photodetectors

Abstract

Recently, the GeO2 thin film has attracted intense attention due to its ultrawide optical bandgap energy (>4 eV), endowing it with quite a promising application for solar-blind photodetectors (SBPDs). Although many epitaxial growth strategies of GeO2 thin films have been achieved, the design for the controllable GeO2 SBPDs is still rarely reported, thus hampering its development as next-generation optoelectronic devices. Here, we deposited pure GeO2 films with ultrawide bandgap energies of around 5.81 eV using the radio frequency magnetron sputtering method and fabricated back-gated three-terminal SBPDs based on GeO2/p-Si heterojunction structures. Subsequently, boosted optoelectronic characteristics at 213 nm, including a lower dark current of 93.52 pA, a higher photon-to-dark-currents ratio of 98.88, and a larger breakdown drain-source voltage (VDS) over 30 V, are demonstrated due to the introduction of SiO2 layer between the GeO2 film and the Si substrate. More importantly, by applying the various voltages on the gate voltage (VGS) of the GeO2/SiO2/p-Si three-terminal SBPDs, a significant change in the threshold VDS is achieved in the range from −21.91 to 8.16 V, demonstrating that the VGS can effectively regulate the turn-on VDS of the device. The obtained results can be instructive for the high-performance SBPDs based on GeO2 films, and our findings will provide a promising approach for achieving high-performance GeO2-based SBPDs.