Recent studies have shown the application of amorphous carbon as a semiconductor in C/Si heterojunction photovoltaic solar cells. In this letter, we report the rectifying current–voltage characteristics of the phosphorus-doped carbon/undoped-carbon (n-C/p-C) junction. The p- and n-carbon films were deposited by pyrolysis and ion-beam sputtering, respectively, on a p-Si substrate, using camphor as a natural carbon precursor. The preliminary photovoltaic characteristics of the cell reveals a short-circuit current density of 17.1 mA/cm2, open-circuit voltage of 0.339 V, and photoelectrical conversion efficiency of 1.82%, a reproducible result, under air mass zero and 1 sun illumination conditions. The spectral photoresponse characteristics of the cell of the above configuration was explained in terms of transmission/absorption characteristics of the two individual carbon layers. © 2000 American Institute of Physics.