Figure 4.
Ultra-fast thermal emission from hBN encapsulated graphene layer (a) the fabricated device, where it consists of a single-layer graphene encapsulated with hBN from both sides and edges are connected with source and drain contacts. (b) The response of light emitter under static electric field F = 4.2 V/um depicts insignificant variations in the intensity of light emission and current density. (c) The response of light emitters under different values of electric field and electric power under the vacuumed condition and air, respectively, under high electric response F = 5.0 V/um, peak emission of 718 nm near-infrared is observed. (d) Demonstrates the electronic temperature and derived temperature together under high biasing conditions, the Tap of hBN and graphene are almost equal; however, it is lower than the electronic temperature. (e) The pulse response from ultrafast light emitter under electric control, where light pulses are verified by the time associated with single-photon counting, (e) The ultrafast light pulses (92 ps) from graphene-based light emitters, where solid blue line depicts electrically drive pulse of 80 ps, which refers to the bandwidth of 10 GHz. (f) The red line corresponds to the thermal radiations and transient temperature exponential fit where schematic at the left-top side presents the energy relaxation time in the graphene layer [96].