Solid-State Impact-Ionization Multiplier With P-N Junction Injection Node

The Solid-state Impact-ionization Multiplier (SIM) was designed to amplify signals from arbitrary current sources through impact ionization. A primary application is amplification of signals produced by photodiodes. Photodiodes made from any semiconductor can be wired directly to the SIM's injection node. In previous versions of the SIM, this injection node was a Schottky contact to silicon. This paper describes a SIM design that injects electrons into the SIM's depletion region through a p-n junction. The injection node is analyzed including how the node's floating voltage changes versus input current. Devices were made using epitaxial silicon and modeled using commercial software. The measured gain characteristics match closely to simulated results and are influenced by high electric fields near the SIM's depletion region edges. Measured frequency response was dominated by charging effects related to the floating node, leading to a response that scales with the inverse of the input current.