AVS 62nd International Symposium & Exhibition
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuM

Paper EM-TuM4
Stress-Directed Compositional Patterning of SiGe Substrates for Lateral Quantum Barrier Manipulation

Tuesday, October 20, 2015, 9:00 am, Room 210E

Session: Beyond CMOS: Materials and Devices for a Post CMOS Era
Presenter: Sang M. Han, University of New Mexico
Authors: S. Ghosh, University of New Mexico
D. Kaiser, University of Pennsylvania
J. Bonilla, University of New Mexico
T. Sinno, University of Pennsylvania
S.M. Han, University of New Mexico
Correspondent: Click to Email
For large-scale manufacturing of single-electron transistors, the capability to form an addressable 2D array of quantum dots would prove useful. While vertical stacking of quantum well and dot structures is well established in heteroepitaxial semiconductor materials, however, manipulation of quantum barriers in the lateral direction in a uniform array poses a significant engineering challenge. Here, we demonstrate lateral quantum barrier manipulation in a crystalline SiGe alloy, using structured mechanical fields to drive compositional redistribution. To apply stress, we make use of a nano-indenter array that is pressed against a Si0.8Ge0.2 wafer in a custom-made mechanical press. The entire assembly is then annealed at high temperatures, during which the larger Ge atoms are selectively driven away from areas of compressive stress. Compositional analysis of the SiGe substrates reveals that this approach leads to a transfer of the indenter array pattern to the near-surface elemental composition, resulting in near 100% Si regions underneath each indenter and a natural pathway to quantum barrier modulation. The process is studied in detail using multiscale computer simulations that demonstrate its robustness across a wide range of applied stresses and annealing temperatures. We computationally explore a carefully chosen set of indenter arrangements to show that Ge atoms can be focused into dots. We expect that this “stress transfer” method can be applied to other crystalline alloys in a scalable way.