title: Ultrahigh Responsivity-Bandwidth Product in a Compact InP Nanopillar Phototransistor Directly Grown on Silicon.
abstract: Highly sensitive and fast photodetectors can enable low power, high bandwidth on-chip optical interconnects for silicon integrated electronics. III-V compound semiconductor direct-bandgap materials with high absorption coefficients are particularly promising for photodetection in energy-efficient optical links because of the potential to scale down the absorber size, and the resulting capacitance and dark current, while maintaining high quantum efficiency. We demonstrate a compact bipolar junction phototransistor with a high current gain (53.6), bandwidth (7 GHz) and responsivity (9.5 A/W) using a single crystalline indium phosphide nanopillar directly grown on a silicon substrate. Transistor gain is obtained at sub-picowatt optical power and collector bias close to the CMOS line voltage. The quantum efficiency-bandwidth product of 105 GHz is the highest for photodetectors on silicon. The bipolar junction phototransistor combines the receiver front end circuit and absorber into a monolithic integrated device, eliminating the wire capacitance between the detector and first amplifier stage.
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720, United States of America.
authors.forename: Wai Son
authors.initials: WS
authors.lastname: Ko
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720, United States of America.
authors.forename: Indrasen
authors.initials: I
authors.lastname: Bhattacharya
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720, United States of America.
authors.forename: Thai-Truong D
authors.initials: TD
authors.lastname: Tran
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720, United States of America.
authors.forename: Kar Wei
authors.initials: KW
authors.lastname: Ng
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720, United States of America.
authors.forename: Stephen
authors.initials: S
authors.lastname: Adair Gerke
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720, United States of America.
authors.forename: Connie
authors.initials: C
authors.lastname: Chang-Hasnain