Eur. Phys. J. B 24, 463-468 (2001)
https://doi.org/10.1007/s10051-001-8699-9

Hopping conductivity and activated transport in InxGa_1-xAs quantum wells

¹ Departamento de Electrónica, Tecnología de Computadoras y Proyectos, Universidad Politécnica de Cartagena, C/Doctor Fleming s/n, 30202 Murcia, Spain
² Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain

Corresponding author: ^a aurbina@upct.es

Received: 6 June 2001
Revised: 16 October 2001
Published online: 15 December 2001

Abstract

We present measurements of the diagonal R_xx and off-diagonal R_xy magnetoresistance under quantum Hall conditions on several high electron mobility transistors (HEMT) based on In_xGaAs quantum wells. From the magnetoresistance tensor we obtain the longitudinal conductivity . We study the transport mechanisms near the minima at temperatures ranging between 2 K and 35 K; activated transport is the dominant mechanism for temperatures above 7 K while variable range hopping conductivity is significant for lower temperatures. We show that electron-electron correlations should be taken into account to explain the conductivity vs temperature behaviour below 5 K. Finally, we study the behaviour of the localization length as a function of Landau level filling and obtain a critical exponent .