Self-organized gate stack of Ge nanosphere/SiO2/Si1-xGex enables Ge-based monolithically-integrated electronics and photonics on Si platform

Abstract

We report the first-of-its-kind, self-organized gate stack of Ge nanosphere (NP) gate/SiO2/Si1-xGex channel fabricated in a single oxidation step. Process-controlled tunability of the Ge NP size (5–90nm), SiO2 thickness (2–4nm), and Ge content (x = 0.65–0.85) and strain engineering (εcomp = 1–3%) of the Si1-xGex are achieved. We demonstrated Ge junctionless (JL) n-FETs and photoMOSFETs (PTs) as amplifier and photodetector, respectively, for Ge receivers. LG of 75nm JL n-FETs feature ION/IOFF > 5×10⁸, ION > 500µA/µm at VDS = 1V, T= 80K. Ge-PTs exhibit superior photoresponsivity >1,000A/W and current gain linearity ranging from nW–mW for 850nm illumination. Size-tunable photo-luminescence (PL) of 300–1600nm (NUV-NIR) are observed on 5–100nm Ge NPs. Our gate stack of Ge NP/SiO2/Si1-xGex enables a practically achievable building block for monolithically-integrated Ge electronic and photonic ICs (EPICs) on Si.