Seamless MoTe₂ Homojunction PIN Diode toward 1300 nm Short‐Wave Infrared Detection

Abstract

Homojunction PN and PIN diodes based on 2D transition metal dichalcogenide (TMD) MoTe2 are reported in this work. Up to date, for PN junction diodes, type II‐based heterojunction diodes are mainly seen in report, but homojunction PN diodes using 2D‐layered materials are still rare although they enable seamless integration. Recently, hydrogen (H)‐doped n‐type MoTe2, achieved via atomic layer deposition (ALD) on top of a p‐type MoTe2 surface, was reported. Consequently, a lateral homojunction PN diode was realized by H‐doping. In fact, MoTe2‐based devices with a thickness on the order of nanometers can be applied for short‐wave infrared (SWIR) detection in the range of ≈1300 nm, a wavelength that Si‐based devices cannot properly address. Here, a seamless MoTe2 homojunction PIN diode is demonstrated, achieving the detection of visible to 1300 nm SWIR photons. This thin MoTe2 initially forms a PN junction by selective H‐doping, but a PIN diode is even obtained using two split gates. Compared to the PN diode mode, the PIN mode greatly enhances the photoresponse in the visible to 1300 nm wavelength range because of the increased built‐in electric field. The Franz–Keldysh effect is regarded strongly responsible for the effective absorption of 1300 nm SWIR photons in MoTe2. It is anticipated that this development may support Si photodetectors for integration on Si devices.

An Ultrafast WSe2 Photodiode Based on a Lateral p-i-n Homojunction

“…The realization of high-performance diodes depends crucially on high-quality p-n junctions and low resistance Ohmic contacts. To create TMDs based homogeneous p-n junction, a variety of doping techniques have been adopted in pioneering studies, including the electrostatic doping with local gate or ferroelectric polarization, − substitutional doping , and surface charge transfer doping by using a range of chemical dopants. − On the other hand, a balanced yet highly efficient carrier injection through low resistance contact is required to enhance drive currents for real application of TMDs based p-n diodes. However, this is rarely demonstrated in aforementioned reports.…”

MoTe2 PN Homojunction Constructed on a Silicon Photonic Crystal Cavity for High-Performance Photodetector

“…(c, d) Performance comparisons of our fabricated device with other 2D materials PN homojunctions and MoTe 2 -based photodetectors. References: BP, ,, graphene, , MoS 2 , , MoTe 2 , ,− , MoSe 2 , and WSe 2 . ,,, …”

High-Performance van der Waals Junction Field-Effect Transistors Utilizing Organic Molecule/Transition Metal Dichalcogenide Interface

“…Here, we deliberately use rare earth metal, Yb with very small work function, − to achieve a large band bending (or full charge carrier depletion) in MoTe 2 (but Au is coated on Yb for protection). The Cytop polymer covers the whole device surface to strengthen the p - type polarity of the ungated MoTe 2 region, using its own C–F dipoles inside. − The electrical conduction properties of a few-nanometer-thin MoTe 2 flake are observed in current–voltage ( I – V ) curves of Figure c, where two terminal measurements initially show very good conduction with the Pt electrode but the conduction current becomes 4 orders of magnitude decreased by thermal evaporation of the Yb Schottky gate on top. Subsequent Cytop spin coating seems to elevate the conduction but only by a half order.…”