Single-fabrication-step Ge Nanosphere/SiO2/SiGe heterostructures: A key enabler for realizing Ge MOS devices

We report channel and strain engineering of self-organized, gate-stacking heterostructures comprising Ge-nanosphere gate/SiO ₂ /SiGe-channels. An exquisitely controlled dynamic balance between the concentrations of oxygen, Si, and Ge interstitials was exploited to simultaneously create these heterostructures in a single oxidation step. Single-crystalline (100)/(110) Si _1-x Ge _x shells with Ge content as high as x= 0.85/0.35 and with a compressive strain of 3%/1.5% were achieved. Our high Ge-content, highly-stressed SiGe shells feature a high degree of crystallinity, providing a “building block” for the fabrication of Ge-based MOS devices.