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Germanium Quantum Technology Solutions

01 /What can CMOS technology do for quantum computing? 02 /Semiconductor devices and scaling with industrial approach 03 /Semiconductor foundry facilities: the good and the bad for qubits 04 /IMEC's latest qubit developments 05 /Summary and outlook 06 /Semiconductors for spin qubits 07 /Germanium quantum wells on silicon 08 /Germanium quantum wells on silicon-germanium 09 /Growth methods 10 /Characterization techniques 11 /Electrical characterization of germanium quantum wells 12 /Fabrication of H-FET 13 /Semiconductor qubits: vision and challenges 14 /Quantum materials 15 /Quantum dot qubits and their operation 16 /Types of quantum dot qubits 17 /Qubit Readout 18 /Qubit Control 19 /Qubit Coherence and Fidelity 20 /Multi-qubit control and quantum algorithms 21 /Quantum links and scaling 22 /Physics of holes 23 /Hole spin qubits 24 /Introduction to electronics for quantum computing 25 /Room temperature electronics 26 /Cryogenic qubit chip carriers 27 /Contribution to IGNITE 28 /Quantum Control Stack for Spin Qubits 29 /What is auto-tuning? 30 /Neural network tuning 31 /Navigating charge stability diagrams 32 /Experimental implementation 33 /Towards universal quantum algorithms 34 /Classical error correction 35 /Quantum error correction 36 /Progress and challenges 37 /Introduction to quantum algorithms 38 /The first algorithms 39 /Quantum annealing 40 /Quantum Machine Learning

Germanium quantum wells on silicon

True or False: The roughness of the virtual substrate is critical because if the peak-valley roughness range reaches values similar to the QW thickness, the QW may be physically isolated into detached regions.

False.

The roughness of the virtual substrate may be a few nm rms, or 10-20 nm peak-valley, but this roughness (coming mainly from a characteristic “crosshatch” associated with strain relaxation in cubic semiconductors, as in Fig. 2 of Hans von Känel, Carsten Rosenblad, Matthias Kummer, Elisabeth Müller, Thomas Graf, and Thomas Hackbarth. Fast Deposition Process for Graded SiGe Buffer Layers. Jpn. J. Appl. Phys. 39 (4B) 2050--2053 (2000) https://iopscience.iop.org/article/10.1143/JJAP.39.2050) tends to be over lateral scales of several microns. The QW grows conformally on this surface. On the scales typically seen in transmission electron microscopy images, for example Fig. 1 of Hans von Känel, Matthias Kummer, Giovanni Isella, Elisabeth Müller, and Thomas Hackbarth. Very high hole mobilities in modulation-doped Ge quantum wells grown by low-energy plasma enhanced chemical vapor deposition. Appl. Phys. Lett. 80 (16) 2922--2924 (2002) https://aip.scitation.org/doi/10.1063/1.1470691, it is not possible to see the roughness from crosshatch.