A spin transistor consisting of a metallic pseudo-spin-valve emitter, a copper base, and a p-n junction collector was prepared on a Si(100) wafer. This spin transistor can provide high magnetocurrent output, high magnetocurrent variation, and high transfer ratio. The common collector configuration with an emitter bias of 5.12V at 77K gives a large magnetocurrent variation of more than 95.5μA in the collector, and the change is more than 3400% with a transfer ratio of 2.59×10−3. At room temperature, these changes go down to 98.3μA and 55.3%, respectively, and the transfer ratio rises to 5.98×10−3. The high performance of this spin-valve transistor is due to the use of a p-n junction as an energy barrier to select spin electrons.