Dual-Color Photodetection Based on Speed-Differentiated Photoresponse with High Photogain

Abstract

Dual-color photodetection can increase detection accuracy due to the specific information from different wavelengths. Traditional dual-color detectors are based on double optical modules or photovoltage devices, which suffer from huge system weight or low gain. In this Letter, a novel dual-color photodetector with Ge/Graphene/CdS sandwich profile is proposed. While visible and infrared light is mainly absorbed by the CdS and Ge layers, respectively, photoelectrical signals from two wavelengths both conducted by graphene are extracted on time-sequence with different sampling frequencies. Based on a tailored interface process and epitaxy InGaAs instead of bulk Ge layer, the difference in response speed more than 3 orders of magnitude (76 kHz/14 Hz) was realized. Due to the photogating effect, the high gain was obtained for both wavelengths, and a photoresponse enhancement originated from the overlapping of local photogating field is observed. The device provided a new solution for high-gain and CMOS-compatible dual-color photodetection.

Secondary electron emission and photoemission from a negative electron affinity semiconductor with large mean escape depth of excited electrons

“…Thus, since λ , B, and ε are independent of E po [39][40][41] and Eqs. ( 2), (6), and (24), equation ( 29) can also be deduced from Eqs. ( 2), (6), and (24).…”

“…Therefore, since λ , B, and ε are independent of E po [39][40][41] and from Eqs. ( 2), (6), and ( 28), the ratio of δ H to δ h relative to a NEASLD can be expressed as…”

“…From Eqs. ( 2), (6), and (28), the fact that λ , B, and ε are independent of E po [39][40][41] and that K(E po , ρ, Z) at H ≥ E po ≥ h keV of a NEASLD can be approximated as a constant K(E po , ρ, Z) ChH , we can derive Eq. ( 28) with respect to E po and obtain the relationships among parameters of a NEASLD…”

“…Therefore, NEASs have more applications in current amplifiers, photo-injectors (such as RF photocathode guns in accelerators) and x-ray sources. [3][4][5][6] Therefore, NEASs are an important topic. [7][8][9][10][11] A NEAS with high E pom (> 20.0 keV) and large λ (> 1.0 × 10 4 Å) is called a NEAS with large λ (NEASLD), where λ is mean escape depth of secondary electrons and E pom is the incident energy of primary electrons E po corresponding to δ m .…”

Red‐Sensitive Image Array Based on Defect‐Engineered PBDB‐T/WSe1.5‐WSe2/Graphene Heterostructure

“…Based on image sensor arrays, the object's shape and color can be sensed similarly to human eyes. [4][5][6][7][8] 2D heterostructures, consisting of diverse 2D materials with van der Waals contacts [9] (like MoS 2 -graphene), have been reported as human eye-inspired soft implantable optoelectric devices, stimulating the optic nerves for perceived images.…”