Study on Schottky barrier reduction and carrier transport mechanism in Au/graphene/CZT heterojunction detectors

To address the prevalent challenges of high metal–semiconductor contact barriers and limited carrier collection efficiency in cadmium zinc telluride (CZT) radiation detectors, this study proposes a non-destructive interface regulation strategy using a graphene van der Waals buffer layer. Unlike traditional chemical etching or surface passivation, this approach leverages the exceptional chemical stability and tunable work function of graphene. It effectively optimizes energy band matching at the Au/CZT interface while preventing the formation of a Te-rich damaged layer. Au/Graphene/CZT/Au detectors were fabricated via a wet-transfer process. Raman spectroscopy (I_2D/I_G ≈2.0, FWHM ≈40 cm⁻¹) confirmed the high-quality monolayer characteristics of the interfacial graphene. By integrating temperature-dependent I–V measurements with TCAD numerical simulations, the physical mechanism through which the graphene interlayer reduces the Schottky barrier is elucidated—specifically, by preventing direct metallization damage and optimizing work function matching and energy band alignment at the Au/Graphene/CZT interface. Results demonstrate that incorporating graphene significantly reduces the Schottky barrier height from 0.508 to 0.309 eV, facilitating a transition in the carrier transport mechanism from trap-limited space charge-limited current (SCLC) toward a symmetric, quasi-Ohmic regime. Performance evaluations reveal that under a 100 V bias, the energy resolution for ²⁴¹Am at 59.5 keV γ-rays improved from 9.4 to 6.6%, accompanied by a 156% increase in the full-energy peak count rate. Furthermore, under 80-keV X-ray excitation, the saturated photon count rate increased by 12.5%. This research establishes a process-compatible, stable, and reliable new route for interface engineering in high-performance, low-noise, and high-flux CZT radiation detectors.