Investigation of the avalanche multiplication characteristics in advanced avalanche photodiodes (APDs)

Abstract

Advanced semiconductor technology has enabled APDs with narrow multiplication widths, but such application has been limited due to poor performance predicted by the McIntyre’s expression, which is based on the local assumption that ignores the dead space effects of the impact ionization process. Using the RPL model, dead space effects in APDs are simulated and when the dead space is significant, there is a significant noise reduction observed. This provides significant incentive to use APDs with narrow multiplication widths to exploit the dead space effects. Simulation results have also suggested that high performing APDs with low excess avalanche noise can be achieved with narrow multiplication widths unlike McIntyre’s prediction. Device simulation based on the Random Path Length model is carried out using a software developed based on the NET4.0 framework with C# in this project. Based on our simulation results, a correction to the McIntyre’s expression based on the ratio of dead space to multiplication width has been proposed to allow accurate noise prediction for APDs. Our proposed correction fits our simulation data well, and will be submitted for publication. An experimental system for excess noise measurement in APDs is also being set up. Characterization of the system is carried out, and theoretical expectations of circuit response and gain of the systems are compared and verified against actual measurements.