We present experimental results on low frequency noise in amorphous PIN diodes under
forward bias by pulses and by direct current. We have developed a new method using a differential
amplifier to measure the noise in pulse regime. The study separates the white noise and the 1/f noise
depending on current levels. The white noise can be evaluated by the shot noise through the various
interfaces damped by their dynamic impedance. The excess noise shows a behaviour in f−1/2, due to
defects in the intrinsic zone and a current dependence in I3/2 , current limited by the NN+ junction.