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

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.