Responsivity Enhancement of Wafer-Bonded In0.53Ga0.47As Photo-Field-Effect Transistor on Si Substrate via Equivalent Oxide Thickness Scaling

Abstract

A high-responsivity photo-field-effect transistor (photo-FET) with a metal-oxide-semiconductor (MOS) structure is a promising technology for low-intensity light detection with its high gain and low operation voltage. To enhance their responsivity, the equivalent oxide thickness (EOT) scaling is one of the effective solutions, which is a common technology to improve the electrical properties of MOSFETs using higher-k insulators. Herein, the EOT scaling effect on the optoelectrical characteristics of photo-FETs using Al2O3 and Al2O3/HfO2 gate stacks is investigated. Thanks to the EOT scaling effect introducing Al2O3/HfO2, only the transconductance of the photo-FET is enhanced without any significant change in the photovoltaic effect and cavity effect. As a result, its responsivity is improved by up to 1.7 times. The results give a basic strategy of the EOT scaling effect for photo-FETs; thus, the EOT scaling with a higher-k insulator is a powerful solution for the high-performance InGaAs photo-FET requiring high responsivity in the short-wavelength infrared range.