Electron mobility enhancement in an undoped Si/SiGe heterostructure by remote carrier screening

We investigate the effects of surface tunneling on electrostatics and transport properties of two-dimensional electron gases (2DEGs) in undoped Si/SiGe heterostructures with different 2DEG depths. By varying the gate voltage, four stages of density-mobility dependence are identified with two density...

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Bibliographic Details
Published in:Journal of applied physics 2019-06, Vol.125 (23)
Main Authors: Su, Yi-Hsin, Chou, Kuan-Yu, Chuang, Yen, Lu, Tzu-Ming, Li, Jiun-Yun
Format: Article
Language:English
Subjects:
Applied physics
Density
Dependence
Electron mobility
Electrostatics
Heterostructures
Saturation
Screening
Silicon germanides
Transport properties
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Summary:We investigate the effects of surface tunneling on electrostatics and transport properties of two-dimensional electron gases (2DEGs) in undoped Si/SiGe heterostructures with different 2DEG depths. By varying the gate voltage, four stages of density-mobility dependence are identified with two density saturation regimes observed, which confirms that the system transitions between equilibrium and nonequilibrium. Mobility is enhanced with an increasing density at low biases and, counterintuitively, with a decreasing density at high biases as well. The density saturation and mobility enhancement can be semiquantitatively explained by a surface tunneling model in combination with a bilayer screening theory.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.5094848