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Non-metallic conduction in Si MOSFETS at low temperatures
Surface Science 98 (1980) 243 0 North-Holland Publishing Company Yamada Science Foundation
NON-METALLIC
and
CONDUCTION IN Si MOSFETS AT LOW TEMPERATURES
D.J. BISHOP, D.C. TSUI and R.C. DYNES Bell Laboratories, Murray Hill, New Jersey 07974, Received
16 October
USA
1979
We have made four-terminal dc transport measurements on n-channel Si MOSFETs at temperatures from T = 0.05to 10 K and have observed, at low T, nonohmic behavior, which varies as the resistance per square (Ro) of the channel. When Ro is higher than -10 ka/U, it depends exponentially on T,in the limit of zero source-drain field (i.e., E -+0).When R is lower than -10 ka/El, it depends logarithmically on T as E -+0 and also logarithmically on E as T -+0.We have studied devices on (111) as well as (100) Si surfaces and found that this result depends only on Ro, and does not depend on the density, the mobility, or the effective mass of the electrons. Our results can be understood by the model of electron heating in two-dimensional conduction, proposed by Anderson, Abrahams and Ramakrishnan [ 1] for the nonlinear behavior observed in thin metal films by Dolan and Osheroff [2]. They give additional support for the scaling theory of localization by Abrahams, Anderson, Licciardello and Ramakrishnan [3], which predicts that there is no true metallic behavior for conduction in two dimensions. R. of a Si MOSFET can be changed continuously by changing the gate voltage, or the substrate bias. The change-over from the exponential behavior to the logarithmic behvior at R. - 10kQ/O, was observed in each of our samples with widely varying mobilities [4].
References [l] P.W. Anderson, E. Abrahams and T.V. Ramakrishnan, Phys. Rev. Letters 43 (1979) 718. [2] G.J. Dolan and D.D. Osheroff, Phys. Rev. Letters 43 (1979) 721. [3] E. Abrahams, P.W. Anderson, D.C. Licciardello and T.V. Ramakrishnan, Phys. Rev. Letters 42 (1979) 673. [4] D.J. Bishop, D.C. Tsui and R.C. Dynes, Phys. Rev. Letters 44 (1980) 1153.
243
NON-METALLIC
and
CONDUCTION IN Si MOSFETS AT LOW TEMPERATURES
D.J. BISHOP, D.C. TSUI and R.C. DYNES Bell Laboratories, Murray Hill, New Jersey 07974, Received
16 October
USA
1979
We have made four-terminal dc transport measurements on n-channel Si MOSFETs at temperatures from T = 0.05to 10 K and have observed, at low T, nonohmic behavior, which varies as the resistance per square (Ro) of the channel. When Ro is higher than -10 ka/U, it depends exponentially on T,in the limit of zero source-drain field (i.e., E -+0).When R is lower than -10 ka/El, it depends logarithmically on T as E -+0 and also logarithmically on E as T -+0.We have studied devices on (111) as well as (100) Si surfaces and found that this result depends only on Ro, and does not depend on the density, the mobility, or the effective mass of the electrons. Our results can be understood by the model of electron heating in two-dimensional conduction, proposed by Anderson, Abrahams and Ramakrishnan [ 1] for the nonlinear behavior observed in thin metal films by Dolan and Osheroff [2]. They give additional support for the scaling theory of localization by Abrahams, Anderson, Licciardello and Ramakrishnan [3], which predicts that there is no true metallic behavior for conduction in two dimensions. R. of a Si MOSFET can be changed continuously by changing the gate voltage, or the substrate bias. The change-over from the exponential behavior to the logarithmic behvior at R. - 10kQ/O, was observed in each of our samples with widely varying mobilities [4].
References [l] P.W. Anderson, E. Abrahams and T.V. Ramakrishnan, Phys. Rev. Letters 43 (1979) 718. [2] G.J. Dolan and D.D. Osheroff, Phys. Rev. Letters 43 (1979) 721. [3] E. Abrahams, P.W. Anderson, D.C. Licciardello and T.V. Ramakrishnan, Phys. Rev. Letters 42 (1979) 673. [4] D.J. Bishop, D.C. Tsui and R.C. Dynes, Phys. Rev. Letters 44 (1980) 1153.
243