Poling-tunable self-powered ultraviolet-C photodetection in mechanochemically derived HfO2–Ga2O3–ZnO/polyethyleneimine composite films

Abstract

Distinct from previously reported HfO2/Ga2O3 layered heterostructures, in which HfO2 1–2 nm insulating interlayer was used and the device operated mainly under external bias, our work presents a mechanochemically derived HfO2–Ga2O3–ZnO multicomponent composite, a PEI-modified interface, a self-powered response at 0 V, and negative pre-poling used to tune the zero-bias response/noise balance. Polyethyleneimine (PEI) was used as a surface and interfacial modifier to form HGZO@PEI films with improved optoelectronic characteristics. Space-charge-limited current (SCLC) analysis yielded an effective electron mobility of 2.01 × 10−2 cm2 V−1 s−1 for HGZO@PEI, higher than the values obtained for the HfO2–ZnO (HZO), Ga2O3–ZnO (GZO), HfO2–Ga2O3 (HGO), and HGZO counterparts under the reported analysis conditions. Under 254 nm ultraviolet-C (UVC) illumination, the device exhibited repeatable zero-bias photoresponse and retained 94.6% of its initial photocurrent after seven days and 85.44% after 50 cycles. Importantly, the HGZO@PEI device operates in a self-powered mode without requiring electrical pre-poling, while negative pre-poling provides an additional means to tune the interfacial electronic environment and balance photoresponse against noise characteristics. This material–interface–field engineering strategy offers a distinct route toward low-power, tunable solar-blind UVC photodetection.