Title: Black Phosphorous-based Multifunctional Broken-Gap Heterojunction

Speaker: Dr. Budhi Singh, IUAC New Delhi

Abstract: The finite energy band-offset that appears between band-structures of employed materials in a broken-gap heterojunction exhibits several interesting phenomena. Although recent experiments have provided evidence of diverse current-transport across broken-gap heterojunctions equipped with different material combinations, tunable functionality across a specific broken-gap heterojunction and a corresponding explanation have remained elusive until now. Here by employing the black phosphorous (BP)/rhenium disulfide (ReS 2 ) heterojunction, we exploit the tunability of BP work function (Ф BP ) with variation in flake thickness in order to demonstrate that a BP-based broken-gap heterojunction can manifest diverse current-transport such as gate tunable rectifying p-n junction diodes, Esaki diodes, backward-rectifying diodes and non-rectifying devices as a consequence of band-structure alignment at the heterojunction. Optoelectronic experiments on the Esaki diode and the p-n junction diode reveal that this diversity of current-transport derives from Ф BP modulation. Additionally, the p + -n-p junction comprising thick-BP/ReS 2 /thin-BP demonstrates multifunctionality of binary and ternary- inverters as well as exhibiting the behavior of a bipolar junction transistor with common-emitter current gain up to 50.