Abstract
Si/SiGe heterostructures are of high interest for high-mobility transistor and qubit applications, specifically for operations below . In order to optimize parameters such as charge mobility, built-in strain, electrostatic disorder, charge noise, and valley splitting, these heterostructures require Ge concentration profiles close to monolayer precision. Ohmic contacts to undoped heterostructures are usually facilitated by a global annealing step activating implanted dopants, but compromising the carefully engineered layer stack due to atom diffusion and strain relaxation in the active device region. We demonstrate a local laser-based annealing process for recrystallization of ion-implanted contacts in SiGe, greatly reducing the thermal load on the active device area. To quickly adapt this process to the constantly evolving heterostructures, we deploy a calibration procedure based exclusively on optical inspection at room temperature. We measure the electron mobility and contact resistance of laser-annealed Hall bars at temperatures below and obtain values similar or superior to that of a globally annealed reference sample. This highlights the usefulness of laser-based annealing to take full advantage of high-performance Si/SiGe heterostructures.
1 More- Received 11 December 2023
- Accepted 14 March 2024
DOI:https://doi.org/10.1103/PhysRevMaterials.8.043801
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