HIGH-SPEED GAAS METAL-SEMICONDUCTOR-METAL PHOTODETECTORS WITH RECESSED METAL ELECTRODES

The GaAs metal‐semiconductor‐metal photodetector (MSM‐PD) with recessed metal electrodes have been fabricated and characterized. The recessed structure allows very short photocarrier sweep‐out time because of both a strengthened electric field in the active region and a shortened distance for the photocarriers to reach the electrodes. Improved high‐speed performance and enhanced peak amplitude in the temporal response can thus be obtained simultaneously. There is about a 60% and 50% improvement in the fall time and peak amplitude of the temporal response at 5 V bias over the conventional device, respectively. The measured results also show that high‐speed operation can be achieved at a lower bias voltage for the GaAs MSM‐PD with recessed metal electrodes as compared to the conventional one. Two‐dimensional simulation was carried out to give an insight into the operation principle of this device.