Visible to Mid-Infrared Photodetector Based on Black Phosphorous-MoS2 Van Der Waals Heterojunction

van der Waals heterostructures of black phosphorous(BP) and Molybdenum Disulfide(MoS2) is designed and evaluated for photodetection application from visible to mid-infrared wavelength up to 4.5 mu m. The device possesses a low dark current less than 0.1 mu A for short wavelength light. For visible and near infrared radiation, the contribution of heat and photo energy to current enhancement is analyzed. Dark current drift by joule heat and laser heat absorbed is observed in short waveband. The difference in response speed is believed to be a result of the competition of BP and MoS2 photocurrent. Gate tunable response time and on-off ratio makes the device versatile in potential application. For mid infrared radiation, BP-MoS2 heterojunction with a dedicated thickness tailoring of MoS2 exhibits similar negative response as an intrinsic BP. The normalized detectivity is D-* of 2.02 x 10(8) Jones for the 4.5 mu m mid-infrared radiation. Elaborate reduction of the noise is conducted to get the time resolvable photo-response. A low bias is necessary for a time resolved photocurrent, reducing the flicker noise to an acceptable level.

Automated summary

van der Waals heterostructures of black phosphorous (BP) and Molybdenum Disulfide (MoS2) were designed and evaluated for photodetection applications from visible to mid-infrared wavelengths. The device exhibited a low dark current for short wavelength light, and the contributions of heat and photo energy to current enhancement were analyzed. The response speed was determined by the competition of BP and MoS2 photocurrent, and the device showed gate tunable response time and on-off ratio for versatile potential applications. For mid-infrared radiation, the BP-MoS2 heterojunction exhibited a negative response similar to intrinsic BP when MoS2 thickness was tailored. The normalized detectivity was 2.02 x 10(8) Jones for 4.5μm mid-infrared radiation. Noise reduction was conducted to achieve time-resolvable photo-response, and a low bias was necessary to reduce flicker noise to an acceptable level.