Fig. 1. Schematic of suspended graphene device and characterization test. (a) Schematic of device structure and Raman spectrum measurement of thermal conductivity; (b) SEM image of suspended graphene device; (c) Raman spectrum of few layer suspended graphene (FLG); (d) field effect curve of FLG transistor

Fig. 2. Variable temperature Raman spectra of graphene and frequency changes of G peak and 2D peak. (a) Variable temperature Raman spectra of FLG at 100-400 K; (b) graphene G peak frequency at different temperatures and calculated first-order temperature coefficient χG; (c) graphene 2D peak frequency at different temperatures and calculated first-order temperature coefficient χ2D

Fig. 3. Raman spectrum of G peak of FLG at zero bias voltage and shift of G peak frequency with laser power. (a) Raman spectra of G peak of FLG at two laser powers; (b) change of G peak frequency of FLG with laser power

Fig. 4. Relationship between G peak frequency of FLG and laser power under different bias voltages

Fig. 5. Relationship between temperature of FLG and bias voltage or thermal conductivity obtained by experiment and calculation. (a) Relationship between temperature and bias voltage; (b) relationship between thermal conductivity and temperature

Table 1. Calculated thermal conductivity and temperature of FLG under different bias voltages according to Raman G peak frequency variation

Table 2. Comparison on thermal conductivity of graphene