Frequency-dependent, rectification current in metal-semiconductor-metal detectors

Recent experiments show that variation in rectification current with ac-bias frequency exists in metal-semiconductor-metal (MSM) detectors. In this letter, we theoretically study the frequency-dependent rectification current in MSM detectors. Under transient bias voltage the MSM detector shows two of the following transient current responses: 1) a fast one related to the displacement current and 2) a slow one related to the removal of carriers from the detector. Rectification current exists in asymmetric MSM detectors and varies not only with ac voltage and optical power, but also with ac-bias frequency. The theoretical results agree with observed experimental results.