Two-Dimensional Silicon-Carbon System And Its Optoelectronic Device Applications

The discovery of graphene opened a door for the interdisciplinary research of two-dimensional (2D) materials’ physics and device. Graphene, with excellent electrical, optical and mechanical properties, has attracted the attentions of numerous scientists worldwide. However, the zero band gap of monolayer graphene limits its application for logic circuits and optoelectronic devices. In order to overcome this disadvantage of graphene, several methods have been taken into consideration, such as nitrogen doped graphene and synthesizing other 2D materials. Under this background, the 2D silicon-carbon system was firstly proposed experimentally:including 2D SiC, SiC2 and silicon doped graphene (SiG); In this thesis, we have investigated the application of 2D silicon-carbon system, especially optoelectronic devices, indicating the potential photovoltaic of 2D silicon-carbon system. The major contributions of this thesis include:(1) 2D SiC and SiC2 have been synthesized via chemical vapor deposition (CVD), stable 2D SiC2 was firstly produced and the concept of 2D silicon-carbon system was proposed.(2) Monolayered SiG was synthesized through the reaction between CH4 and SiH4 via CVD, the measurement demonstrated that the silicon atoms were substitutional doped into graphene lattice at a doping level of 3.4 at%.(3) According to the first-principle simulation, the band gap of graphene, with 3.3 at% silicon concentration, is direct and can reach 0.28 eV. The work function of SiG with 3.4 at% Si dopant is 0.13 eV larger than that of graphene.(4) SiG/GaAs heterostructure was fabricated, the power conversion efficiency (PCE) of SiG/GaAs heterostructure solar cell was improved for 33.7% in average as compared to that of graphene/GaAs solar cell.(5) SiG can effectively convert infrared light into electricity, through spin-coating the SiG to the surface of the graphene/GaAs heterostructure, the PCE of the graphene/GaAs solar cell was improved by 14.6% when compared to that of graphene/GaAs solar cell without SiG.