Polarity Modulation of Hot Electron Transfer in Plasmonic Au Nanoparticle/GaN Heterojunctions: Implications for Quantum Efficient Plasmon-Driven Devices

Abstract

The efficiency of hot electron injection caused by noble metals varies based on the Schottky barrier height at the interface of metal−semiconductor plasmonic heterojunctions, which ultimately affects the energy conversion efficiency of plasmonic heterojunction devices. Herein, the efficiency of hot electron injection was improved by regulating the Schottky barrier through the effects of spontaneous polarization and piezoelectric polarization. The freestanding Ga-polar and N-polar planes were prepared by electrochemical selective etching. Based on the freestanding different polar plane GaN, the Au nanoparticles (NPs)/N-polar plane GaN and Au NPs/Ga-polar plane GaN plasmon heterostructures were prepared. The study analyzed the hot carrier dynamics through transient absorption spectroscopy and compared the injection efficiency of Au NPs/Ga-polar GaN and Au NPs/N-polar GaN. The injection efficiency of hot electrons of the Au NPs/N-polar GaN heterostructure is 2.8 times higher than that of the Au NPs/Ga-polar GaN heterostructure. Meanwhile, the hot electron injection efficiency of Au NPs/N-polar GaN improves due to the reduction of the Schottky barrier under the tensile strain. This study presents a unique research proposition and remedy toward the primary technical barrier of low quantum efficiency in interface hot carrier transfer of plasmon-driven apparatus.