Khondaker, S I , Shlimak, I S , Nicholls, J T , Pepper, M and Ritchie, D A (1999) Two-dimensional hopping conductivity in a delta-doped GaAs/AlxGa1-xAs heterostructure. Physical Review B, 59 (7).
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We present zero magnetic-field resistivity measurements of the variable-range hopping (VRH) in a two-dimensional electron gas created at a delta-doped GaAs/AlxGa1-xAs heterostructure. When either the temperature or carrier density are reduced the longitudinal resistivity shows a crossover from two-dimensional Mott VRH, rho(T)= rho(M) exp (T-M/T)(1/3) to Efros-Shklovskii (ES) Coulomb-gap behavior rho(T) = rho(ES) exp (T-ES/T)(1/2). In both regimes, near the crossover, the data collapse onto universal curves with a temperature independent prefactor rho(M)approximate to(1/2)(h/E-2) Or rho(ES)approximate to h/e(2). The latter result is in close agreement with measurements of Si metal-oxide-semiconductor held-effect transistors. We discuss the possible implications of our data on the theory of phonon-assisted VRH. [S0163-1829(99)01108-X].
This is a Submitted version This version's date is: 15/2/1999 This item is not peer reviewed
https://repository.royalholloway.ac.uk/items/ca513d51-1de7-943f-8012-e9a69b994b4d/4/
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