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Title: Scattering mechanisms in shallow undoped Si/SiGe quantum wells

We report the magneto-transport study and scattering mechanism analysis of a series of increasingly shallow Si/SiGe quantum wells with depth ranging from ~ 100 nm to ~ 10 nm away from the heterostructure surface. The peak mobility increases with depth, suggesting that charge centers near the oxide/semiconductor interface are the dominant scattering source. The power-law exponent of the electron mobility versus density curve, μ ∝ nα, is extracted as a function of the depth of the Si quantum well. At intermediate densities, the power-law dependence is characterized by α ~ 2.3. At the highest achievable densities in the quantum wells buried at intermediate depth, an exponent α ~ 5 is observed. Lastly, we propose and show by simulations that this increase in the mobility dependence on the density can be explained by a non-equilibrium model where trapped electrons smooth out the potential landscape seen by the two-dimensional electron gas.
 [1] ;  [2] ;  [1] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. National Taiwan Univ., Taipei (Taiwan); National Nano Device Labs., Hsinchu (Taiwan)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 2158-3226; AAIDBI; 607423
Grant/Contract Number:
Accepted Manuscript
Journal Name:
AIP Advances
Additional Journal Information:
Journal Volume: 5; Journal Issue: 10; Journal ID: ISSN 2158-3226
American Institute of Physics (AIP)
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
77 NANOSCIENCE AND NANOTECHNOLOGY quantum wells; electron gas; heterojunctions; surface charge; tunneling