Low-temperature Schottky barrier tunneling in InSb/InxAl1-xSb quantum well heterostructures

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.