avalanche photodiode pulse characteristics

Discussion in 'Physics' started by amidpl, Aug 27, 2012.

  1. amidpl

    Thread Starter New Member

    Oct 5, 2011
    Hello all,
    I'm working with silicon avalanche photodiodes, and was wondering how one might define the current pulse one produces from incident photons. My semiconductor physics is a bit rusty, but let me describe it as well as I can. We are working with x-rays, so the wavelengths are between 0.01 to 10 nm wavelengths. The photodiodes that we work with are reverse biased, between 400V to 1800V. There are two types of photodiodes that we work with, one is better for short wavelengths, and one is better for long wavelengths. The lower bias diode is used for short wavelengths(higher energy x-rays). The diode capacitance is about 120pF. They have a responsivity of 16 A/W, but this is measured using visible light(530nm), not x-rays, so I'm not sure if that is useful. Response times are quoted around 5 to 15 nsec. I'm kind of unfamiliar with some of these parameters. I assume response time refers to the time required for a photon to induce a charge pulse. I'm interested in how one would predict the intensity of the charge/current pulse, the approximate shape, and the duration.