A MONTE CARLO PARTICLE STUDY OF A SEMICONDUCTOR RESPONDING TO A LIGHT PULSE

A picosecond photodetector has been simulated by means of the Monte Carlo particle model. The detector consists of a 2 |im film of n-type GaAs, doped uniformly with 1 0 " donors m~"3. The film is covered with metal strips 2 pxti apart. Every second strip is equally biased, the others earthed. The simulated response to a femtosecond flash is a current which peaks after about 1 ps, and dies down within 10 ps. No current is observed for biases below a threshold of IV. This device promises therefore to be operable for pulses at frequencies up to 100 GHz. The flash generates a stationary electron-hole plasma, only a few carriers escape to form the response current pulse. The remainder of the plasma will eventually be eliminated by recombination