Various carbon based spintronic materials or devices have been made by pulsed laser deposition. It is found that amorphous carbon (a-C) film shows a very large magnetoresistance (MR) of 27% at B=7T and 2 K. It is also found that the a-C/Si heterojunction shows a memory effect at 80 K. A solar cell with structure of Fex-C1-x/Al2O3/Si has been made which shows a power conversion efficiency of 2.01% with AM1.5 illumination. Our work show that carbon and silicon can be used to make a hybrid material/device which shows many novel structural dependent physical properties, such as MR, memory effect and photovoltaic effect.