actfel device modeling via spice

ACTFEL Device Modeling via SPICE

ACTFEL Device Modeling via SPICE

J. P. Bender and J. F. Wager

Department of Electrical and Computer Engineering

Center for Advanced Materials Research

Oregon State UniversityCorvallis, Oregon 97731-3211http://www.ece.orst.edu/~jfw

Organization:Organization:

• Fowler-Nordheim Diode Model

• Double-sheet Charge Model

Fowler-Nordheim Diode ModelFowler-Nordheim Diode Model

q

qm

mm

qJ B

B

FN 3

*24exp

*16

23

0

2

22

Fowler-Nordheim Diode model: Q-VFowler-Nordheim Diode model: Q-V

Fowler-Nordheim Diode model: C-VFowler-Nordheim Diode model: C-V

Fowler-Nordheim model: Transient

response

Fowler-Nordheim model: Transient

response

Fowler-Nordheim model: Transferred

Charge Curve

Fowler-Nordheim model: Transferred

Charge Curve

Fowler-Nordheim Model

Experimental Data

FN Model Scaling with Varying Vmax

FN Model Scaling with Varying Vmax

Modified Fowler-Nordheim Diode ModelModified Fowler-Nordheim Diode Model

Double-sheet Charge ModelDouble-sheet Charge Model

Two-sheet Charge Model Band DiagramTwo-sheet Charge Model Band Diagram

Two-sheet Charge Model Equivalent Circuit

Two-sheet Charge Model Equivalent Circuit

Two-sheet Charge ModelTwo-sheet Charge Model1. Emission Mechanisms

– Field emission (pure tunneling)

– Thermal emission– Trap-to-band impact ionization

2. Charge CaptureThe probability that an electron crossing a sheet of charge is captured depends on:– Electric field at the sheet– Occupancy of the sheet

Two-sheet Charge ModelTwo-sheet Charge ModelSpace Charge Creation via Field Emission

Two-sheet Charge ModelTwo-sheet Charge ModelSpace Charge Creation via Trap-band Impact Ionization

Two-sheet Charge Model: Static Space Charge

Two-sheet Charge Model: Static Space Charge

• Ionized traps are not allowed to refill

• B= 1.5 V (experimental value)

• Bulk trap depth = 1.38 V

Transferred Charge Capacitance Overshoot (Two-sheet charge model)

Fowler-Nordheim Diode model

Experimental Data

ConclusionsConclusions

Fowler-Norheim Diode• Simple yet accurate SPICE model for

devices without space charge

Two-sheet Charge Model• Demonstrates mapping of device

physics to SPICE• Large amounts of C-V overshoot in

SPICE