The application of silicon nanocrystals (Si-NC) is somewhat limited due to their low luminescence intensity. Therefore, it is of interest to investigate methods for enhancing the luminescence intensity of Si-NC. In this study, phosphorus (P)-doped Si-NC with two different doping methods were prepared by electron beam thermal evaporation: in-situ doping (during synthesis) and ex-situ doping (after synthesis). The photoluminescence (PL) intensity and crystallinity of Si-NC can be enhanced through phosphorus doping. Moreover, a comparison between two different methods of Si-NC doping reveals that the luminescence intensity of in-situ P-doped Si-NC is superior to that of ex-situ P-doped Si-NC, which is increased by an order of magnitude compared to the PL intensity of undoped Si-NC.