Hot Electron Tunneling in Pt/LaAlO3/SrTiO3 Heterostructures for Enhanced Photodetection

LaAlO3/SrTiO3 (LAO/STO) heterostructures, in which a highly mobile two-dimensional electron gas (2DEG) is formed, have great potential for optoelectronic applications. However, the inherently high density of the 2DEG hinders the observation of photo-excitation effects in oxide heterostructures. Herein, a strong photoresponse of the 2DEG in a Pt/LAO/STO heterostructure is achieved by adopting a vertical tunneling configuration. The tunneling of the 2DEG through an ultrathin LAO layer is significantly enhanced by UV light irradiation, showing a maximum photoresponsivity of similar to 1.11 x 10(7)%. The strong and reversible photoresponse is attributed to the thermionic emission of photoexcited hot electrons from the oxygen-deficient STO. Notably, the oxygen vacancy defects play a critical role in enhancing the tunneling photocurrent. Our systematic study on the hysteresis behavior and the light power dependency of the tunneling current consistently support the fact that the photoexcited hot electrons from the oxygen vacancies strongly contribute to the tunneling conduction under the UV light. This work offers valuable insights into a novel photodetection mechanism based on the 2DEG as well as into developing ultrathin optoelectronic devices based on the oxide heterostructures.

Automated summary

This study achieved a strong photoresponse of the 2DEG in a Pt/LAO/STO heterostructure with a maximum photoresponsivity of about 1.11 x 10(7)% by adopting a vertical tunneling configuration. Oxygen vacancy defects played a critical role in enhancing the tunneling photocurrent, and research consistently supported the contribution of photoexcited hot electrons from the oxygen vacancies to tunneling conduction under UV light.