Physical Vapor Deposition of High-Mobility P-Type Tellurium and Its Applications for Gate-Tunable van der Waals PN Photodiodes.

Recently, tellurium has attracted resurgent interest due to its outstanding p-type characteristics and 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 1450 cm/(V s), which is, to the best of our knowledge, the highest among existing synthesized two-dimensional p-type semiconductors. The high mobility of Te enables the fabrication of Te/MoS PN diodes with highly gate-tunable characteristics. The Te/MoS heterostructure is demonstrated to be used as visible-light photodetectors with a current responsivity up to 630 A/W, which is about 1 order of magnitude higher than one achieved using p-type Si-MoS PN photodiodes. The photoresponse of Te/MoS heterojunctions also exhibits strong gate tunability due to their ultrathin thickness and unique band alignment. The successful synthesis of high-mobility Te and its integration into Te/MoS photodiodes show promise for the development of highly tunable and multifunctional photodetectors.