Oxygen vacancies-assisted carrier transport toward improved Au/HfO2−x/Si Schottky photodetectors

Abstract

Au/Si Schottky junctions are important building blocks for fabricating inexpensive and efficient photodetectors (PDs), whereas Si surface defects induce severe interfacial non-radiative recombination that markedly degrades the performance of the resulting devices. Herein, oxygen vacancy (VO)-rich HfO2−x thin films are employed to passivate Si surface defects to fabricate improved Au/HfO2−x/n-Si Schottky PDs. It shows that HfO2 thin films effectively passivate n-Si surface defects, while the presence of VO defects compromises the passivation efficiency. This results in improved Au/HfO2/n-Si Schottky PDs, but the improvements are limited by inefficient interfacial hole transport caused by the insulating HfO2. In contrast, the interfacial hole transport is markedly enhanced in HfO2−x thin films owing to VO defect-assisted hole tunneling, thereby leading to highly improved Au/HfO2−x/n-Si Schottky PDs. These results demonstrate that efficient interfacial carrier transport is vital for realizing improved dielectric-passivated PDs and provide a promising pathway for fabricating high-performance Si-based heterojunction PDs.