Sensitively Site‐Dependent Enhancement of Emissions from Ge Quantum Dots in SiGe Microdisks

High quality factor of AlN microdisks embedding GaN quantum dots

Undoped accumulation-mode Si/SiGe quantum dots.

We report on a quantum dot device design that combines the low disorder properties of undoped SiGe heterostructure materials with an overlapping gate stack in which each electrostatic gate has a dominant and unique function-control of individual quantum dot occupancies and of lateral tunneling into and between dots. Control of the tunneling rate between a dot and an electron bath is demonstrate...

Giant electro-optic effect in Ge/SiGe coupled quantum wells

Silicon-based photonics is now considered as the photonic platform for the next generation of on-chip communications. However, the development of compact and low power consumption optical modulators is still challenging. Here we report a giant electro-optic effect in Ge/SiGe coupled quantum wells. This promising effect is based on an anomalous quantum-confined Stark effect due to the separate c...

Electrostatically defined quantum dots in a Si/SiGe heterostructure

We present an electrostatically defined few-electron double quantum dot (QD) realized in a molecular beam epitaxially grown Si/SiGe heterostructure. Transport and charge spectroscopy with an additional QD as well as pulsed-gate measurements are demonstrated. We discuss technological challenges specific to silicon-based heterostructures and the effect of a comparably large effective electron mas...

Valley splitting in Si quantum dots embedded in SiGe

We examine energy spectra of Si quantum dots embedded in Si0.75Ge0.25 buffers using atomistic numerical calculations for dimensions relevant to qubit implementations. The valley degeneracy of the lowest orbital state is lifted and valley splitting fluctuates with monolayer frequency as a function of the dot thickness. For dot thicknesses 6 nm, valley splitting is found to be 150 eV. Using the u...