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Research Activities

JJ Simulation | IARPA Josephson Junction Modeling

Ongoing effort to bring TCAD simulation tools to digital superconducting technology.

Current Deliverables

Currently the contract is centered on accurately simulating the process steps involved in the manufacturing of digital superconducting devices in 2D. These process steps consist of oxide deposition, sputtering, metal oxidation, and anodization.

Current Investigation

Our group seeks to develop an understanding of the key parameters in superconducting device design. Efforts toward this goal include the aforementioned process modeling as well as device modeling. Device modeling consists of both microscopic and mesoscopic methods for proper simulation of device operation. The microscopic model we are investigating is the tight-binding Bogoliubov-de Gennes (BdG) Hamiltonian. We are also exploring magnetic effects as well as long junction effects using the phenomenological sine-Gordon equation.

Future/Potential Work

  • Process modeling
    • Make the tool capable of handling 3D
    • Simulation of niobium grain structure
    • Incorporation of molecular dynamics
  • Device modeling
    • Microscopic
      • Continued investigation of the BdG Hamiltonion
      • Possible incorporation of molecular dynamics
    • Mesoscopic
      • Simulation of long junctions to be used for test structures
      • Continued simulation of magnetic effects

DTRA Contract Ga2O3 Radiation Effects

Ga2O3 Radiation Effects:
Objective: To understand the low and high dose stability of β-phase of Gallium Oxide to neutrons, electrons and protons, in order to simulate common radiation environments. Measure fundamental parameters such as carrier removal rate, energy level and thermal stability of traps and role of hydrogen.

Method: Unique coupling of theory and experiment to produce a detailed understanding of the effects of radiation on this promising wide bandgap semiconductor and a predictive capability for new radiation hardened materials and components.

Ga2O3 Examples

Ga2O3 Publications

DTRA Contract - AlGaN Radiation Effects

Summary of Key FLOODS Simulation Results for Proton Radiation Effects:

  • Insights Into Underlying Physical Mechanics
  1. Mobility degradation can be explained by ionized impurity scattering from radiation-generated point source defects
  2. Ionized acceptor traps are responsible for positive Vt shift and reduction in Ids and gm; however, compensation by ionized donor traps mitigate severity of degradation
  3. Degradation of small signal AC and RF performance can be modeled primarily with static defect trap states
  • New TCAD Modeling Capability in FLOODS as a Result of Simulation Needs
  1. Calculation of partial ionization of static traps using technique to improve convergence (trap energy spread)
  2. Small signal analysis capability using sinusoidal steady-state analysis technique
  3. Incorporation of multiple trap states in small signal or transient simulation

AlGaN Radiation Examples

AlGaN Radiation Modeling Publications

This paper is one of the most downloaded over the last year. S.J. Pearton, F. Ren, Erin Patrick, M.E. Law, and Alexander Polakov, “Review – Ionizing Radiation Damage Effects on GaN Devices”, ECS Journal of Solid State Science and Technology, 5(2) Q35-60, 2016.

AFOSR MURI - AlGaN Reliability

This effort ran from 2008-2013. Work on reliability for AlGaN is highlighted here - Reliability MURI

Chemical Sensor Simulation

We are aiming to understand the operation of chemical sensors with an initial focus on pH sensors. In particular, we are looking to understand and model two dimensional effects and drain bias on the sensitivity of the sensor.



FLOOXS Software

FLOOXS was developed largely with support from the Semiconductor Research Corporation (SRC). The development effort won the 1993 SRC Technical Excellence Award.


This is the main page for the FLOOXS (FLOOPS, FLOODS, FLOORS) wiki manual. FLOOXS stands for the FLorida Object Oriented Device, Process and Reliability Simulator, using the old unix wild card convention of x taking the place of either "P", "R", or "D". The codes are built as a single executable (FLOOXS) and are configured with different sets of default variables for each purpose (FLOOPS/FLOODS/FLOORS).

License and Download Information

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