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We propose a model, validated with simulations, describing how band-to-band tunneling (BBT) affects the leakage current degradation in some irradiated fully-depleted SOI devices. It is demonstrated that the drain current dependence on total ionizing dose at negative gate bias can result from the combination of BBT and charge buildup in the BOX, including the transition to the high current state. The role of impact ionization is examined. [ABSTRACT FROM AUTHOR]

A hierarchical method for total dose effects simulation of large mixed signal circuits using VHDL-AMS is described. Simplified behavioral models (or macro-models) of small sub-circuits replace SPICE-level circuits. The behavioral models describe the electrical circuit behavior and its dependence on the radiation dose. The behavioral models of sub-circuits can be assembled into complex mixed signal circuits. As a result, the computational cost is reduced significantly compared to conventional SPICE-based methods. The VHDL-AMS method also allows bias-dependent total dose degradation to be coupled to the circuit and operational conditions. Simulation accuracy remains sufficient to determine critical performance metrics of the circuit as the circuit performance degrades with dose. [ABSTRACT FROM AUTHOR]