Numerical simulation of heavy ion charge generation and collection dynamics

Abstract

This paper describes a complete simulation approach to investigating the physics of heayy-ion charge generation and collection during a single event transient in a PN diode. The simulations explore the effects of Werent ion track models, applied biases, background dopings, and LET on the transient responses of a PN diode. The simulation results show that ion track structure and charge collection via diffusiondominated processes play important roles in determining device transient responses. The simulations show no evidence of rapid charge collection in excess of that deposited in the device depletion region in typical funneling time frames (i.e., by time to peak current or in less than 500 ps). Further, the simulations clearly show that the device transient responses are not simple functions of the ion's incident LET. The simulation results imply that future studies and experiments should consider the effects of ion track structure in addition to LET and extend transient charge collection times tb insure that reported charge collection efficiencies include diffusiondominated collection processes.

Numerical Simulation of Transient Response in 3-D Multi-Channel Nanowire MOSFETs Submitted to Heavy Ion Irradiation

“…Previous works have demonstrated that the different charge generation distributions used for the radial ion track does affect the device transient response, but the variation is typically limited to ~5% for ion strikes on bulk p-n diodes (Dodd, 2005;Dussault et al, 1993). Considering a LET which is not constant with depth along the path has a more significant impact on the transient response in bulk devices.…”

“…Considering a LET which is not constant with depth along the path has a more significant impact on the transient response in bulk devices. The key parameters of the single event transient (peak current, time to peak and collected charge) have up to 20% variation when LET is allowed to vary with depth compared to the case of a constant LET (Dussault et al, 1993). Nevertheless, the LET variation with depth has no influence on the transient response of actual SOI devices with thin Silicon film.…”

“…One of the most interesting models is the "non-uniform power law" track model, based on the Katz theory (Kobetich & Katz, 1968) and developed by Stapor (Stapor & McDonald, 1988). In this model, the ion track has a radial distribution of excess carriers expressed by a power law distribution and allows the charge density to vary along the track (Dussault et al, 1993). Other analytical models propose constant radius nonuniform track or Gaussian distribution non-uniform track.…”

High-energy heavy-ion-induced charge transport across multiple junctions

“…Carrier concentrations above 10 cm-3 can extend to radii of more than a micron within a highenergy heavy ion track such as the 1.7 GeV 197Au and 1. 9 GeV 1271 ions used in this research [1,2]. Additionally, highenergy heavy ions have sufficient ranges to penetrate deep within a device, creating potentially conductive paths through regions of the device usually isolated during normal operation.…”

3-D Quantum Numerical Simulation of Transient Response in Multiple-Gate Nanowire MOSFETs Submitted to Heavy Ion Irradiation

“…One of the most interesting models is the "non-uniform 75 power law" track model, based on the Katz theory (Kobetich & Katz, 1968) and developed by Stapor (Stapor & McDonald, 1988). In this model, the ion track has a radial distribution of excess carriers expressed by a power law distribution and allows the charge density to vary along the track (Dussault et al, 1993). Other analytical models propose constant radius nonuniform track or Gaussian distribution non-uniform track.…”