Boron doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films are deposited by using 13.56 MHz plasma enhanced chemical vapor deposition as an emitter layer for SHJ solar cells. By changing different deposition parameters such as precursors gas flow rate and plasma power density, various thin films have been deposited and electrical and optical properties have been investigated. By introducing the carbon into the structure optical band gap of the window layer increased up to 2.0 eV. The experimental results show that for (p) a-SiCx:H thin film with optical band gap of 1.9 eV the parasitic absorption in short wavelength region of the spectrum has been decreased. The short current density has been improved to 38.93 mAcm-2 with absolute gain of 0.5 mAcm-2 in comparison to conventional SHJ solar cell.