Characterization of Dynamic Behaviour of Metal-Semiconductor-Metal Photodetectors by Correlation Technique

The frequency response, linearity, and sensitivity of metal-semiconductor-metal (MSM) photodetectors are investigated. A new measurement technique is presented for examination of the dominant effects on current transport. The technique is based on optical excitation of a device by subsequent pulses of varying delay and on correlation of the pulse responses. In combination with time domain measurements an efficient technique for material and device optimization is attained. Characterization of the MSM-photodetectors results in a short risetime (800 fs) and pulse width (9 ps) and excellent linearity using n-type epitaxial layers. In contrast to semiinsulating layers no pulse tails are observed.