Physical Vapor Deposition of High Mobility P-type Tellurium and its Applications for Gate-tunable van der Waals PN Photodiodes

TL;DR

This paper reports a novel physical vapor deposition method to synthesize high-mobility tellurium nanoflakes, enabling the creation of highly tunable van der Waals pn photodiodes with superior optoelectronic performance.

Contribution

The study introduces a substrate engineering approach for high-quality Te nanoflakes with record-high mobility, leading to advanced gate-tunable pn diodes and photodetectors.

Findings

Achieved a hole mobility of 1500 cm2/Vs in Te nanoflakes.

Demonstrated Te/MoS2 photodiodes with responsivity up to 630 A/W.

Showed strong gate tunability in the heterostructure's photoresponse.

Abstract

Recently tellurium (Te) has attracted resurgent interests due to its p-type characteristics and outstanding ambient environmental stability. Here we present a substrate engineering based physical vapor deposition method to synthesize high-quality Te nanoflakes and achieved a field-effect hole mobility of 1500 cm2/Vs, which is, to the best of our knowledge, the highest among the existing synthesized van der Waals p-type semiconductors. The high mobility Te enables the fabrication of Te/MoS2 pn diodes with highly gate-tunable electronic and optoelectronic characteristics. The Te/MoS2 heterostructure can be used as a visible range photodetector with a current responsivity up to 630 A/W, which is about one order of magnitude higher than the one achieved using p-type Si-MoS2 PN photodiodes. The photo response of the Te/MoS2 heterojunction also exhibits strong gate tunability due to their ultrathin thickness and unique band structures. The successful synthesis of high mobility Te and the enabled Te/MoS2 photodiodes show promise for the development of highly tunable and ultrathin photodetectors.