High-performance MSM photodetector based on MgZnO/InGaO heterojunction for solar-blind UV detection

Abstract

A solar-blind metal–semiconductor–metal ultraviolet photodetector (UVPD) based on a MgZnO/InGaO (MZO/IGO) heterojunction (MIH) was fabricated. The presence of self-trapped holes in the non-bonding p-orbitals of oxygen vacancies in IGO endows it with high photoconductive gain characteristics. The built-in electric field of MIH effectively depletes the majority carriers in the dark. The Au electrode and upper IGO film form an ideal ohmic contact, enabling unimpeded carrier transport and thereby enhancing the device's photoconductive gain. The findings reveal that the MIH UVPD achieved a significant photo current of 1.88 mA and a minimal dark current of 0.21 nA at 5 V bias, resulting in an ultrahigh light-to-dark current ratio (8.95 × 106) of 6 orders of magnitude. Under the same bias, MIH UVPD exhibits a notable responsivity (R) of 1.45 × 104 A/W at 260 nm within the solar-blind region, along with a UV/visible light responsivity suppression ratio of 6.04 × 104 (R260 nm/R400 nm) and an impressive detectivity (D*) of 7.88 × 1017 Jones, suggesting its potential for fabricating high-performance solar-blind UVPDs.