Plasma-Engineered High-Performance Tellurium Field-Effect Phototransistors

Abstract

Promising 2D materials suitable for low-temperature processing are crucial for advancing beyond Moore's law. While p-type performance is as essential as n-type in CMOS technology, the development of high-performance p-type 2D materials has lagged behind their n-type counterparts. Here, high-performance p-type tellurium (Te) field-effect transistors (TeFETs) that undergo plasma treatment at low temperatures to enhance their electrical and optoelectrical properties are presented. Ar plasma-treated Te shows significantly improved crystallinity compared to untreated counterparts, confirmed by various characterization techniques. Plasma treatment shifts the Fermi level toward the valence band and induces subgap states near the valence band in the Te film. A valence band offset of 0.2 eV and 30.6% surface flattening are confirmed in plasma-treated TeFETs. The electrical performance of plasma-treated TeFETs exhibits a 20-fold increase in the Ion/Ioff ratio, from 1.2 × 104 to 2.7 × 104, and a 51% reduction in subthreshold swing, from 19.1 to 9.4 V per decade, compared to pristine devices. Stability and bias stress tests show resilience to degradation after plasma treatment. Notably, optoelectrical performance improves due to the trap-assisted photogating effect. These findings provide a promising pathway for improving p-type materials at low temperatures, facilitating their use in various next-generation electronic platforms.