A PIN diode includes a first polycrystalline silicon region doped with a P-type of conductivity, a second polycrystalline silicon region doped with an N-type of conductivity and an intrinsic polycrystalline silicon region. At least the intrinsic polycrystalline silicon region is configured to include fluorine atoms. A polycrystalline silicon bar may include the first polycrystalline silicon region, the second polycrystalline silicon region and the intrinsic polycrystalline silicon region. The polycrystalline silicon bar may be supported by an insulating region within a semiconductor substrate.