Boosting Interface Band Alignment via Synergistic Supercritical Fluid Post-Treatment and SAM Functionalization for Ga2O3-Hybrid Solar-Blind Detectors
p-n heterojunction solar-blind photodetectors based on p-type materials and n-type Ga2O3 have attracted significant attention in optoelectronics due to their inherent low dark current and self-powered operation. Organic-inorganic hybrid heterojunctions integrating p-type organic materials with n-type Ga2O3 offer a promising solution to overcome lattice mismatch, enabling device performance breakthroughs. In this work, Ga2O3 thin films were treated via a supercritical fluid (SC) technique, which significantly reduced defect state density while improving crystallinity and surface uniformity, laying a foundation for heterojunction interface optimization. Simultaneously, a self-assembled monolayer (SAM) was introduced at the organic-inorganic heterojunction interface. The high-quality Ga2O3 surface engineered via SC treatment facilitated efficient, oriented self-assembly of SAM molecules, enabling precise modulation of interfacial energy band alignment and promoting separation and transport dynamics of photogenerated carriers. Benefiting from synergistic SC modification and SAM functionalization, the fabricated solar-blind photodetector achieved a highest responsivity of 111.7 mA/W and a specific detectivity of 1.02 × 10^11 Jones under zero bias (self-powered mode) and weak 254 nm light with an intensity of 5 μW/cm2. These results demonstrate a viable route to high-performance, self-powered solar-blind photodetectors through interface engineering.