Revealing Detailed Transport Mechanisms in Silicon Tunneling Diodes

Abstract

Understanding carrier transport in heavily doped semiconductor junctions is essential for developing next-generation tunneling devices for cryogenic electronics and steep-slope technologies. In this work, we investigate the transport mechanisms in a silicon tunneling diode using extensive TCAD (Technology Computer Aided Design) simulations benchmarked against electrical measurements over a wide temperature range of 4 K to 440 K. The measured device characteristics show no negative differential conductance, strong temperature dependence of forward current with a nearly constant semi-logarithmic slope, and weak temperature dependence under high reverse bias. To identify the mechanisms underlying these characteristics, we investigate the contributions of band-to-band tunneling (BTBT), trap-assisted tunneling (TAT), Shockley-Read-Hall (SRH) recombination, and avalanche generation. We also enhance the Schenk TAT model by incorporating Fermi-Dirac statistics to accurately capture the transport behavior at lower temperatures. Under forward bias, TAT in the depletion region dominates the current at low-to-moderate voltages, whereas SRH becomes increasingly significant at higher voltages and temperatures. Under reverse bias, TAT dominates at low reverse voltages, particularly near and above room temperatures, whereas BTBT becomes predominant at high reverse bias, resulting in weak temperature dependence. This work provides a comprehensive understanding of the bias- and temperature-dependent transport mechanisms in silicon tunneling junctions and an enhanced TAT model suitable over a broader range of operating conditions.