In this work, the characteristics of p-channel Si nano-crystal memory is studied. We have shown that the nano-crystal memory has the feasibility for practical memory application with characteristics of low programming voltage. By comparing the characteristics between the devices with dots and the devices without dots, we have shown that the programming holes are tunneled into dots. The hole tunneling component and the electron tunneling component were separated successfully by independent measurement of the current at the body terminal and at the source/drain terminal of the memory. For small gate voltage, the holes from the inversion layer tunneled into dots during programming. However, for large programming voltage, the electron tunneling from the dot into the substrate becomes dominant. We have also shown that the programmed holes were recombined with the electrons tunneled from the substrate during erasing. And the retention characteristics of programmed holes and electrons is compared. And finally we have shown that the feasible possibility of thin tunneling ON(oxide/nitride) and tunneling nitride as tunneling barrier in nano-crystal memory.