Hot Carrier Transport and Carrier Multiplication Induced High Performance Vertical Graphene/Silicon Dynamic Diode Generator

Abstract

Dynamic semiconductor diode generators (DDGs) offer a potential portable and miniaturized energy source, with the advantages of high current density, low internal impedance, and independence of the rectification circuit. However, the output voltage of DDGs is generally as low as 0.1-1 V, owing to energy loss during carrier transport and inefficient carrier collection, which requires further optimization and a deeper understanding of semiconductor physical properties. Therefore, this study proposes a vertical graphene/silicon DDG to regulate the performance by realizing hot carrier transport and collection. With instant contact and separation of the graphene and silicon, hot carriers are generated by the rebounding process of built-in electric fields in dynamic graphene/silicon diodes, which can be collected within the ultralong hot electron lifetime of graphene. In particular, monolayer graphene/silicon DDG outputs a high voltage of 6.1 V as result of ultrafast carrier transport between the monolayer graphene and silicon. Furthermore, a high current of 235.6 nA is generated due to the carrier multiplication in graphene. A voltage of 17.5 V is achieved under series connection, indicating the potential to supply electronic systems through integration design. The graphene/silicon DDG has applications as an in situ energy source for harvesting mechanical energy from the environment.

Self-Driven Photo-Polarized Water Molecule-Triggered Graphene-Based Photodetector

“…In the top panel, the Raman peaks observed at 1,592.3 and 2,685 cm −1 can be attributed to the G peak and 2D peak of Gr [ 18 , 19 ]. Remarkably, the extremely weak D peak (1,345 cm −1 ) reveals high quality and limited defects of graphene [ 20 ]. The current–voltage ( I – V ) curves of the Gr/W/N-GaN and Gr/W/P-GaN under dark and 350 nm illumination are illustrated in Fig.…”

Broadband Insulator-Based Dynamic Diode with Ultrafast Hot Carriers Process

“…To enrich the application scenarios, flexible graphene film is used here to demonstrate the portable possibility, which may be helpful to promote the area such as real-time health detection, motion analysis, flexible electronic skin, and smart self-powered sensor system. Recently, some reports in the DD area illustrate the enhancement of output voltage, which is contributed to the unique carrier multiplication effect of graphene; however, single/few layers of graphene are needed to maintain the high energy level of HC [ 19 ]. Here, the flexible graphene film (~1000 layers) can also transport the highly energetic rebounded HC without significant loss, and a stable voltage output around ~10 V is reached for a single graphene film/FEP-based DD as shown in Figure 3(e) .…”

“…Dynamic semiconductor physics has emerged as the platform of exploring the novel semiconductor devices since the dynamic Schottky diode has been proposed [ 1 , 2 ]. Since the discovery of DD in 2018 [ 1 ], the novel and ultrafast mechanical-electrical coupling process at the solid-solid/solid-liquid interfacial barrier has been taken seriously due to groundbreaking physical picture, especially the unusual excitation, rebound, and transport of HCs induced by the mechanical input, which has brought the births of various evidences including the dynamic PN/Schottky/heterojunction [ 1 , 3 – 10 ], polarized solution based DD [ 11 , 12 ], tunneling DD [ 2 , 10 ], and nonlinear synergy DD [ 13 – 16 ]; some excellent characters like direct-current output, high current density, flexibility, suitable inner resistance, and easy fabrication have also been proven [ 1 , 2 , 5 ], and the integrable ability has also been illustrated in recent works [ 17 – 19 ]. These devices open an exciting new avenue for recycling in situ mechanical energy efficiently, showing great potential to subvert the current in-situ energy harvest system as the macroscopic electricity output density of these generators has reached over 100 W/m 2 [ 3 , 17 , 20 – 22 ].…”

Infrared Radiation of Graphene Electrothermal Film Triggered Alpha and Theta Brainwaves

“…The graphene film fabricated by the tape casting method has excellent flexibility and mechanical stability, which indicates its superiority for a wearable heating device. [41,42] The top and cross-sectional views of the scanning electron microscopy (SEM) image of the graphene film are shown in Figure 2b,c, respectively, which reveal that the graphene film was flat and composed of vertically stack graphene flake layers less than ten layers. The Raman spectrum of the graphene film at 25 °C was also measured and shown in Figure 2d, which has three peaks named as D-peak (1348 cm À1 ), G-peak (1584 cm À1 ), and 2D-peak (2724 cm À1 ).…”