Crossover phenomenon for two-dimensional hopping conductivity and density-of-states near the Fermi level

The variable range hopping (VRH) resistivity in a gated delta -doped GaAs /AlGaAs heterostructure was measured at temperatures down to 280 mK. At low temperatures, the logarithm of the resistivity follows T super(-1/2) behaviour, which corresponds to the existence of a soft (linear) Coulomb gap in t...

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Veröffentlicht in:	Solid state communications 1999-03, Vol.109 (12), p.751-756
Hauptverfasser:	KHONDAKER, S. I, SHLIMAK, I. S, NICHOLLS, J. T, PEPPER, M, RITCHIE, D. A
Format:	Artikel
Sprache:	eng
Schlagworte:	Condensed matter: electronic structure, electrical, magnetic, and optical properties Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures Electronic transport in interface structures Electronic transport phenomena in thin films and low-dimensional structures Exact sciences and technology Iii-v semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions Low-field transport and mobility piezoresistance Physics
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Zusammenfassung:	The variable range hopping (VRH) resistivity in a gated delta -doped GaAs /AlGaAs heterostructure was measured at temperatures down to 280 mK. At low temperatures, the logarithm of the resistivity follows T super(-1/2) behaviour, which corresponds to the existence of a soft (linear) Coulomb gap in the density of states (DOS) at the Fermi level (FL). As the temperature is increased, there is a crossover to T super(-1/3) behaviour, corresponding to a constant DOS outside the Coulomb gap. A quantitative analysis of the resistivity data allows us to determine the width of the Coulomb gap and the DOS around the FL.
ISSN:	0038-1098 1879-2766
DOI:	10.1016/s0038-1098(99)00027-7