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June 23, 2016

Bipolar Junction Transistors in Two-Dimensional WSe2 with Large Current and Photocurrent Gains

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ACS Publications

The invention of the bipolar junction transistor (BJT) as the first solid state transistor helped to usher in the digital revolution.(1) It is a three-terminal device formed by connecting two p–n junction diodes in a back-to-back configuration and is a critical component in many analog, digital, and sensor applications. The central feature of a BJT is current gain.(2) When the center contact is absent, one can achieve photocurrent gain where the light replaces the function of the middle contact. Transition metal dichalcogenides (TMDs) have attracted great attention because they can be naturally thin,(3) an important consideration in modern transistors,(4, 5) and several novel devices have already emerged.(6-8) In the single-layer form they are direct bandgap materials, which are necessary for optoelectronic devices.(9-12) Here, we demonstrate the BJT device in the exfoliated TMD semiconductor WSe2 with both current and photocurrent gains. In addition, we discuss specific features that enhance these gains from the doping technique we employ. Read more