Epitaxial Growth Of Graphene And Its Characterization

Graphene with excellent electrical and optical properties has broad application in the field of electronics, aerospace, energy. This paper is based on pyrolytic graphite target material, research the best preparation technology of graphene by pulsed laser deposition(PLD), success epitaxial graphene films in single crystal Cu(111) substrate. Finally got the following results:(1) The carbon films were compared with d ifferent deposition pulses in the case of a single variable under high vacuum. We found that the preparation of graphene films was conducive by reduce the deposited pluses number, on the contrary, tends to disordered structure with the increase of deposition numbers. When the pulses number was 100, we have the best deposition number for preparation of graphene films.(2) By comparing the preparation of graphene films under high vacuum with different deposition temperature, we found that temperature was a big difference to the quality of thin film crystallization. With the increase of temperature, carbon film was increase the gradually from the disordering to ordering. We obtained the optimum crystallization quality when growth temperature at 600 °C. If rising temperatures, it wound produces dislocation leading to the crystallization quality decline by lattice mismatch. The optimal growth conditions of graphene was for laser energy 200 m J, laser frequency 1Hz, pulse numbers 100, deposition temperature 600 °C.(3) In hydrogen atmosphere, we found the optimum growth temperature for preparing graphene films is 400 °C. It can be concluded that hydrogen is benefit to decrease the deposition temperature of graphene films. In hydrogen atmosphere, the optimal growth co nditions of graphene was for laser energy 200 m J, laser frequency 1Hz, pulse numbers 100, deposition temperature 400 °C.(4) The optical properties of graphene were tested by uv-vis spectral reflectance, the reflectance in the near ultraviolet band area wa s about 35% and about 90% in the region of the infrared wavelengths, so that the reflectance was the sharp rise in visible band. The optical band gap of graphene films can be calculated by the Kubelka- Munk equation. The result showed the optical band gap of graphene prepared under high vacuum was 2.12 e V, the optical band gap of graphene prepared under hydrogen atmosphere(2×10-1 Pa) was 2.2 e V.(5) The resistance- temperature curve of graphene were tested. It was found that the lowest resistance was 2.93 Ω under the condition of high vacuum(600 ℃, 100 pulses) which has the best conductivity, and the largest resistance was 6.7 Ω under the condition of high vacuum(650 °C, 100 pulses). The temperature coefficient of resistance of graphene was calculated. The results showed that the biggest TCR of graphene was 26% under the condition of hydrogen atmosphere(2×10-1 Pa), which showed that the resistance had the largest change with the change of temperature.