High Responsivity Ge Phototransistor in Commercial CMOS Si-Photonics Platform for Monolithic Optoelectronic Receivers

Abstract

A high-gain phototransistor (PT) is demonstrated on a commercial 90-nm CMOS Si-photonics platform. The Gummel and output characteristics, the gain, and the frequency response of the phototransistorare measured for both optical and electrical inputs. An experimental quantitative agreement has been shown between the electrical and optical performance of the PT, and the implications of having such a device for the design of monolithic optical receivers is discussed. The fabricated PT achieves high responsivityvalues of 53A/W and 80A/W at 1310-nm wavelength, with 1 V and 4V bias voltages, respectively. An optical receiver is simulated based on the proposed PT, achieving 10GHz bandwidth and 40dBΩ transimpedance gain.