3D Amorphous and Polycrystaline Device Simulator

TFT 3D is an advanced device technology simulator equipped with the physical models and specialized numerical techniques required to simulate amorphous or polysilicon devices in 3D. TFT 3D models the electrical effects of the distribution of defect states in the band gap of non-crystalline materials. Users can specify the Density Of States (DOS) as a function of energy for amorphous silicon and polysilicon for grain and grain boundaries as well as the capture cross-sections/lifetimes for electrons and holes. Models for mobility, impact ionization and band-to-band tunneling can be modified to accurately predict device performance.

Features

  • Energy dependent DOS
  • Trap-to-Band phonon-assisted tunneling
  • Band-to-Band tunneling effects
  • Poole-Frenkel barrier lowering
  • DIGBL (Drain Induced Grain barrier Lowering)
  • DC, AC and transient simulation
  • Separate grain and grain boundary DOS specification

Poly-Si TFT Grain Size Simulation

Crystallization by excimer laser annealing helps ELA Poly-Si TFT devices to have very good grain quality. The effects on the channel of the gate position and grain size can be simulated with TFT 3D.

Electron and hole concentrations at 0V bias. The electron and hole concentrations are controlled by the grain and gate shapes.

 

a-Si TFT

The metal electrode geometry is important for devices such a bottom gate a-Si TFTs. TFT 3D correctly accounts for these geometrical effects on the current and capacitance.

A bottom gate a-Si TFT device at Vd=1V.

 

Id/Vd curves for the bottom gate of a a-Si TFT device as the gate bias is varied from 2 to 10V.
Cgd/Vd and Cds/Vd curves for the bottom gate of a a-Si TFT device as the gate bias is varied from 2 to 10V.

 

Solar Cells

Simulation of solar cells in 3D can be used to investigate effects such as electrical losses in the cell structure due to variation in the front metal grid finger geometry.

Potential distribution in a solar cell.
The simulation of an octagonal array of TFT elements using TFT 3D. The contacts and the SiO2 layers have been made transparent so that the amorphous Si elements can be seen more clearly.

 

Rev. 110613_02