Current Density Contribution to Plasmonic Enhancement Effects in Metal–Semiconductor–Metal Photodetectors

This work studies how the local current density in a metal-semiconductor-metal photodetector (MSM PD) corresponds to the plasmonic enhancement and therefore affects the overall enhancement of the device. For this type of semiconductor photodetector, the enhancement of incident light due to plasmonic structures is most critical inside the substrate, where the photocurrent is generated. This work develops a relationship between the total device optical enhancement and the current density by considering the average optical enhancement, weighted by the current density in the GaAs layer of a simulated MSM PD. This corresponds to an increased overall current in the device. Effects of the wire and nanoslit widths on the total weighted optical enhancement were studied. The results showed that both widths have a significant impact on the total weighted optical enhancement, improving it by two orders of magnitude when using the smallest possible wire widths and nanoslits.