Self-Organized Ge Nanospherical Gate/SiO ₂ /Si _0.15 Ge _0.85 -Nanosheet n-FETs Featuring High ON-OFF Drain Current Ratio

We reported experimental fabrication and characterization of Si _0.15 Ge _0.85 n-MOSFETs comprising a gate-stacking heterostructure of Ge-nanospherical gate/SiO ₂ /Si _0.15 Ge _0.85 -nanosheet on SOI (100) substrate in a self-organization approach. This unique gate-stacking heterostructure is simultaneously produced in a single oxidation step as a consequence of an exquisitely controlled dynamic balance between the concentrations of oxygen, Si, and Ge interstitials at 900 °C. Process-controlled tunability of nanospherical gate of 60-100 nm in diameter, gate oxide thickness of 3 nm, and Si _0.15 Ge _0.85 nanosheet with compressive strain of -2.5% was achieved. Superior gate modulation is evidenced by subthreshold slope of 150 mV/dec and I _ON I _OFF >5 × 10 ⁸ (I _OFF < 10 ^-6 μA μm and I _ON >500 μA μm ) measured at V _G = +1V , V _D = +1 V, and T = 80 K for our device with channel length of 75 nm.