pi-gate (π-gate)

**Pi-Gate (Π-Gate)** is a **multi-gate transistor structure where the gate wraps around three sides of the channel** — resembling the Greek letter Π in cross-section, similar to a FinFET but with the gate extending partially down the sidewalls without fully reaching the buried oxide. **What Is a Π-Gate?** - **Structure**: Gate covers top + both sidewalls of the silicon body, but does not touch the BOX. - **Electrostatic Control**: Better than single-gate (planar) but less than gate-all-around (GAA). - **Relation to FinFET**: A FinFET with gate not extending all the way down is effectively a Π-gate. **Why It Matters** - **Short-Channel Control**: Three-sided gate provides better electrostatic control than planar, reducing DIBL and $V_t$ roll-off. - **SOI Compatibility**: Natural fit for SOI substrates where the body sits on BOX. - **Research**: Explored as an intermediate step between planar FD-SOI and full GAA architectures. **Pi-Gate** is **the three-sided embrace** — wrapping the gate around the channel from three directions for improved electrostatic control in ultra-scaled transistors.