Si-rich Si3N4 for Si QD Formation and Simultaneous Donor Modulation Doping of Adjacent Barrier Material (talk)

The thermodynamics of foreign atoms in nano crystals (NCs) shows that conventional doping is not feasible to a degree required for high quality devices. We introduce an adjacent barrier layer to Si3N4 with excess Si for NC formation which can be doped by the same excess Si within the same anneal required for Si NC formation. In III-V super lattices (SLs), modulation doping is the standard approach. Aluminium nitride, gallium nitride and their alloys (AlxGa1−xN, 0 ≤ x ≤ 1) are routinely doped with Si as a donor up to ca. 1020 cm−3. The electronic and thermochemical properties of AlxGa1−xN ensure an excellent fit as matrix materials for the band structure of Si QD super lattices, with high compatibility to Si process technology like co-sputtering of AlxGa1−xN from AlN and GaN targets. The ratio of Al/Ga can be used to tune the barrier heights between the QD arrays. DFT calculations showed that Ga also works as a shallow donor in AlxGa1−xN, 0 ≤ x ≤ 0.3, extending the material range to Ge and SiGe NC in G3N4.