P-Type Tunnel FETs With Triple Heterojunctions

A triple-heterojunction (3HJ) design is employed to improve p-type InAs/GaSb heterojunction (HJ) tunnel FETs. Atomistic quantum transport simulations show, that the added two HJs (AlInAsSb/InAs in the source and GaSb/AlSb in the channel) significantly shorten the tunnel distance and create two resonant states, greatly improving the ON state tunneling probability. Moreover, the source Fermi degeneracy is reduced by the increased source (AlInAsSb) density of states and the OFF state leakage is reduced by the heavier channel (AlSb) hole effective masses. With VDD = 0.3V and IOFF = 1nA/μm, ballistic ION of 606μA/μm (492μA/μm) is obtained at 30nm (15nm) channel length, which is comparable to n-type 3HJ counterpart and significantly exceeding p-type silicon MOSFET. Simultaneously, the nonlinear turn on and delayed saturation in the output characteristics are also greatly improved.