Effect of buffer layer on electrical and photoelectric performance of amorphous Ga2O3 MOSFETs on SiO2/Si substrate

Abstract

In this paper, an enhanced back-gated Ga₂O₃ MOSFET on SiO₂/Si substrate with Al₂O₃ buffer layer was reported. Compared with the direct deposition of Ga₂O₃ films on substrate, the amorphous Ga₂O₃ film with buffer layer has a higher density (5.76 g/cm³) and a lower concentration of oxygen vacancies. The amorphous Ga₂O₃ MOSFET with the buffer layer has a higher mobility of 16.15 cm² V⁻¹ s⁻¹, lower subthreshold swing of 386.14 mV/decade and interface state density of 1.09 × 10¹² cm⁻² eV⁻¹. Although the device with buffer layer structures has a slightly lower responsivity and external quantum efficiency than that without buffer layer, it exhibits a much lower time constant and faster response speed. These results can be attributed to the reduction of trap density within the thin film and at the interface due to the introduction of the buffer layer. Our work also demonstrates the flexible and adjustable characteristics of the photoresponse parameters for three-terminal photodetectors.