1. Tunnel field-effect transistor
Bongjoong Kim

2. Contents Motivation Structure of TFET Band-to-Band Tunneling
Device operation
Homojunction vs Heterojunction
Goal

3. Motivation Subthreshold swing ↓  the transistor speed ↑
Steep-slope devices - Promising candidate for low power electronics

4. Structure of TFET TFET is simply a gated p-i-n diode
MOSFET
TFET
TFET is simply a gated p-i-n diode
electrostatic potential of the intrinsic region is controlled by a gate terminal

5. Band-to-Band Tunneling
MOSFET
TFET
MOSFET – thermal injection mechanism
TFET - band-to-band tunneling

6. Device operation
Off - state
On - state
In the OFF state: Wide potential barrier  no tunneling
In the On state: Gate voltage > threshold voltage  potential barrier becomes narrow tunneling current

7. Device operation
The channel valence band has been lifted above the source conduction band  conductive channel opens
Only carriers in the energy window ΔΦ can tunnel into the channel  the energy distribution of carriers from the source is limited
This filtering function  achieve below 60mV/decade

8. Homojunction vs Heterojunction
Heterojunction can achieve higher tunneling current

9. Goal - Optimization Highest possible ION
- in the range of hundreds of milliamperes
The lowest Savg
- ↓60 mV per decade for five decades of current
Lowest possible IOFF

10. Thank you