The invention provides a semiconductor detector, and the semiconductor detector comprises a semiconductor crystal, a cathode, an anode and at least one ladder electrode; the semiconductor crystal comprises a top surface, a bottom surface and at least one side; the cathode, the anode and the ladder electrode are conductive thin films deposited on a surface of the semiconductor crystal; the cathode is disposed on the bottom surface of the semiconductor crystal, the anode is disposed on the top surface of the semiconductor crystal, the ladder electrode is disposed on the at least one side of the semiconductor crystal; and the ladder electrode comprises a plurality of sub-electrodes. As compared to the prior art, the semiconductor detector can improve the energy resolution.