A radiation detector useable in a downhole tool configured to be positioned in a borehole includes a printed circuit board and at least one detector element coupled to the printed circuit board. The at least one detector element includes a semiconductor direct conversion material for directly converting gamma rays into electrical signals. The semiconductor direct conversion material includes a cathode surface and an anode surface. In addition, the at least one detector element includes a cathode operatively connected to the cathode surface, and an anode operatively coupled to the anode surface. The radiation detector also includes a voltage source coupled to the printed circuit board and configured to provide a voltage to the at least one detector element.