High-Performance Self-Powered Photodiodes Using Engineered Ternary Nitride/GaN Interfaces

Abstract

The global semiconductor industry faces sustainability challenges as III-V compounds rely on increasingly scarce gallium, germanium, and indium. ZnSnN2 (ZTN), composed entirely of earth-abundant elements, represents a viable alternative. However, realizing high-performance ZTN-based devices requires overcoming fundamental heterostructure limitations: interfacial defects from lattice mismatch degrade built-in potentials and increase recombination losses. For emerging applications in IoT networks such as wearable healthcare and remote sensing, self-powered photodiodes offer critical advantages through zero-bias operation, eliminating external power requirements. However, achieving high-power generation under weak illumination remains challenging, requiring optimization of material quality, electrical characteristics, and absorption properties. Here, we demonstrate that controlling Zn/Sn stoichiometry through Ar flow modulation, simultaneously optimizing built-in electric fields and minimizing defect densities at heterointerfaces. Our optimized ZTN/GaN heterostructure incorporates micro-scale surface configuration for enhanced absorption while modifying the trade-off with surface recombination. The devices achieve 101 nW of power and 0.6 V of voltage at zero bias-sufficient to autonomously operate a microcontroller with integrated temperature/humidity sensors. This demonstration establishes earth-abundant ternary nitrides as practical candidates for self-powered sensing systems, addressing both performance and sustainability requirements for next-generation distributed electronics.