Sub-60 Mv/dec Germanium Nanowire Field-Effect Transistors with 2-Nm-thick Ferroelectric Hf0.5Zr0.5O2

We report an n-type Ge nanowire ferroelectric-Hf0.5Zr0.5O2 field effect transistor (Ge NW FE-HZO FET) was experimentally demonstrated. An in-situ ALD O3 treatment was carried out to form an atomically-thin (~0.4 nm) interfacial layer (IL) of GeOx, followed by a 2-nm FE-HZO capped with a 1-nm Al2O3 layer. It is found that microwave annealing (MWA) sample shows better uniformity of FE-HZO properties compared to rapid thermal annealing (RTA). The fabricated Ge NW FE-HZO FET shows minimum subthreshold slope (SSmin) of 55 mV/decade and ION/IOFF ratio of 8.1 × 104 with low hysteresis (30 mV) at drain voltage (VD) of 0.1 V.