Tunnel field-effect transistor Bongjoong Kim

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

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

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

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

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

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

Homojunction vs Heterojunction Heterojunction can achieve higher tunneling current

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

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