In Situ Growth And Structural Controlling Of Graphene/SiC/Si On Si Single Crystal

As a wide bandgap semiconductor,cubic silicon carbide?3C-SiC?is the representative of the third generation of wide bandgap semiconductor substrate materials.At present,the commonly used 3C-SiC preparation method mostly uses tetrachlorosilane?SiCl₄?,silane?SiH₄?,methyltrichlorosilane?CH₃SiCl₃?and other flammable,explosive,toxic or highly corrosive precursors to participate in the reaction.This not only makes the substrate susceptible to corrosion,it also requires safety measures such as explosion-proof,anti-corrosion and exhaust gas treatment,and various alarm facilities are needed around the equipment to ensure safe production.In addition,the graphene film prepared by the conventional chemical vapor deposition method needs to be transferred to a substrate having a high dielectric constant for application,and a large number of defects are easily introduced during the transfer process.At present,methods for directly growing graphene on a semiconductor substrate?SiC?are being actively explored.In this paper,laser chemical vapor deposition?LCVD?technology was used to safely and efficiently prepare SiC films on<111>oriented Si single crystal substrates using only C₃H₈ as the source gas.X-ray diffraction analysis,scanning electron microscopy,Raman spectroscopy,transmission electron microscopy and other analytical techniques were used to analyze the composition and microstructure of SiC films.The effects of carbonization temperature,carbonization time on the preferred orientation,crystallinity,microstructure,growth rate and epitaxial relationship of silicon carbide and various crystal defects were studied.Subsequently,the Graphene/SiC/Si film was grown by laser irradiation of epitaxial SiC film in LCVD vacuum chamber.The effects of laser irradiation temperature and irradiation time on the thickness,single crystal size and quality of epitaxial graphene were studied.The results show that the carbonization temperature ranges from 1373 K to 1623K,and the carbonization time ranges from 1 s to 600 s.The surface of the film is triangular and hexagonal.The carbonization growth rate increases with the increase of carbonization temperature,and the maximum carbonization growth rate is 41.01?m/h at the carbonization temperature of 1623 K.According to the results of the polarogram analysis,in the range of carbonization temperature of 1373-1673 K,the obtained 3C-SiC thin film is<111>oriented epitaxial growth,and the grown thin film contains twin and bidirectional domains,the angle between the twin boundary and the film growth direction is 70.5^o.When the carbonization temperature rises from 1373 K to 1623 K,the void size at the interface increases from 0.828?m to 2.312?m,and the void density decreases from 0.23/?m² to 0.0466/?m²;the void density did not change significantly with increasing carbonization time,but the size increased from0.38?m to 2.18?m.The number,size and quality of graphene layers were controlled by adjusting the laser irradiation temperature and time.The number of graphene layers increases first and then decreases with the increase of growth temperature.When the growth temperature is 1373 K and the irradiation time is 10 s,the minimum number of layers of graphene is three layers.The size of graphene decreases first and then increases with the increase of growth temperature.When the growth temperature is 1373 K and the irradiation time is 10 s,the maximum graphene size is 16.2 nm.The mass decreases first and then increases with the increase of growth temperature.At the growth temperature of 1373 K,the film defect density is the smallest.The precise control of the number of graphene layers was achieved by controlling the graphene growth process.