Wigner solid in two-dimensional electron system in silicon in the extreme quantum limit?

• Published in: Surface science Vol. 305; no. 1; pp. 96 - 100
• Main Authors: Dolgopolov, V.T., Kravchenko, G.V., Kravchenko, S.V., Shashkin, A.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.03.1994
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(94)90866-4

The metal-insulator transition in a 2D electron gas of Si MOSFETs has been investigated. In the extreme quantum limit, the phase boundary in the H, N s plane has been found to be a straight line with the slope ν c = 0.53 ± 0.01. Transport properties of the insulating phase have proven to be unexpectedly similar to those of the insulating phase in GaAs/AlGaAs heterostructures where magnetically induced Wigner solid formation has been reported. Strongly nonlinear current-voltage characteristics with linear V( I) dependence below some threshold voltage, V c, and saturation at V > V c were observed. The longitudinal resistance corresponding to the linear part of the I– V characteristics demonstrates an activated temperature dependence. Knowing the values of the threshold voltage and activation energy we obtain a characteristic length that is large compared to the distance between electrons, which excludes a single-electron picture of nonlinearity. The similarity of transport properties strongly suggests the same physical nature of the insulating phases in Si inversion layers and GaAs/AlGaAs heterostructures. However, the value of ν c is somewhat surprising since, in the presence of a long-range potential, the percolation metal-insulator transition is expected at precisely this filling factor. The percolation transition is considered as an alternative explanation of the observed effects.