We report low-temperature I(V) measurements taken on small area surface metal contacts to InSb/InAlSb quantum well material in the temperature range 4.5-100 K. We obtain Schottky barrier J(V) data under reverse bias and analyze the transport observed by using a tunneling model derived from the three-dimensional density of states, showing close correlation for the majority of devices measured. We consider the "Rowell" analysis Tunneling Phenomena in Solids, edited by E. Burnstein and S. Lundqvist (Plenum, New York, 1969), p. 273 of the zero-bias resistance R-0(T) and differential conductance G(V) for determining the dominant transport mechanism. Two distinct temperature dependences are observed in the R-0(T) data, a weak insulatorlike dependence identifying true single-step tunneling and a strong nonlinear dependence, which we attribute to defect assisted multistep tunneling. Effective barrier parameters are extracted by fitting the G(V) data with a Brinkman-Dynes-Rowell model J. Appl. Phys. 41, 5 (1970) for carrier tunneling.
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