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Title: Fabrication of quantum dots in undoped Si/Si 0.8Ge 0.2 heterostructures using a single metal-gate layer

Abstract

Enhancement-mode Si/SiGe electron quantum dots have been pursued extensively by many groups for their potential in quantum computing. Most of the reported dot designs utilize multiple metal-gate layers and use Si/SiGe heterostructures with Ge concentration close to 30%. Here, we report the fabrication and low-temperature characterization of quantum dots in the Si/Si 0.8Ge 0.2 heterostructures using only one metal-gate layer. We find that the threshold voltage of a channel narrower than 1 μm increases as the width decreases. The higher threshold can be attributed to the combination of quantum confinement and disorder. We also find that the lower Ge ratio used here leads to a narrower operational gate bias range. The higher threshold combined with the limited gate bias range constrains the device design of lithographic quantum dots. We incorporate such considerations in our device design and demonstrate a quantum dot that can be tuned from a single dot to a double dot. Furthermore, the device uses only a single metal-gate layer, greatly simplifying device design and fabrication.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
Work for Others (WFO); USDOE
OSTI Identifier:
1320515
Report Number(s):
SAND2016-8268J
Journal ID: ISSN 0003-6951; APPLAB; 646874
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 109; Journal Issue: 9; Journal ID: ISSN 0003-6951
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Lu, T. M., Gamble, J. K., Muller, R. P., Nielsen, E., Bethke, D., Ten Eyck, G. A., Pluym, T., Wendt, J. R., Dominguez, J., Lilly, M. P., Carroll, M. S., and Wanke, M. C. Fabrication of quantum dots in undoped Si/Si0.8Ge0.2 heterostructures using a single metal-gate layer. United States: N. p., 2016. Web. doi:10.1063/1.4961889.
Lu, T. M., Gamble, J. K., Muller, R. P., Nielsen, E., Bethke, D., Ten Eyck, G. A., Pluym, T., Wendt, J. R., Dominguez, J., Lilly, M. P., Carroll, M. S., & Wanke, M. C. Fabrication of quantum dots in undoped Si/Si0.8Ge0.2 heterostructures using a single metal-gate layer. United States. doi:10.1063/1.4961889.
Lu, T. M., Gamble, J. K., Muller, R. P., Nielsen, E., Bethke, D., Ten Eyck, G. A., Pluym, T., Wendt, J. R., Dominguez, J., Lilly, M. P., Carroll, M. S., and Wanke, M. C. Mon . "Fabrication of quantum dots in undoped Si/Si0.8Ge0.2 heterostructures using a single metal-gate layer". United States. doi:10.1063/1.4961889. https://www.osti.gov/servlets/purl/1320515.
@article{osti_1320515,
title = {Fabrication of quantum dots in undoped Si/Si0.8Ge0.2 heterostructures using a single metal-gate layer},
author = {Lu, T. M. and Gamble, J. K. and Muller, R. P. and Nielsen, E. and Bethke, D. and Ten Eyck, G. A. and Pluym, T. and Wendt, J. R. and Dominguez, J. and Lilly, M. P. and Carroll, M. S. and Wanke, M. C.},
abstractNote = {Enhancement-mode Si/SiGe electron quantum dots have been pursued extensively by many groups for their potential in quantum computing. Most of the reported dot designs utilize multiple metal-gate layers and use Si/SiGe heterostructures with Ge concentration close to 30%. Here, we report the fabrication and low-temperature characterization of quantum dots in the Si/Si0.8Ge0.2 heterostructures using only one metal-gate layer. We find that the threshold voltage of a channel narrower than 1 μm increases as the width decreases. The higher threshold can be attributed to the combination of quantum confinement and disorder. We also find that the lower Ge ratio used here leads to a narrower operational gate bias range. The higher threshold combined with the limited gate bias range constrains the device design of lithographic quantum dots. We incorporate such considerations in our device design and demonstrate a quantum dot that can be tuned from a single dot to a double dot. Furthermore, the device uses only a single metal-gate layer, greatly simplifying device design and fabrication.},
doi = {10.1063/1.4961889},
journal = {Applied Physics Letters},
number = 9,
volume = 109,
place = {United States},
year = {Mon Aug 01 00:00:00 EDT 2016},
month = {Mon Aug 01 00:00:00 EDT 2016}
}

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