Low temperature surface conductivity of GaSb

Abstract

The DC conductivity of p-type GaSb single crystals was measured as a function of temperature (300>T>5K). For different exposure times to air after etching the measured conductivity varied by several orders of magnitude in the low temperature range indicating a dominant surface conduction below approximately 20K. Hall measurements undertaken to characterize the bulk of the crystal also indicate that the surface conductance is associated with an accumulation layer and that the mobility in the surface layer is very low. The associated band bending is calculated in the continuum approximation and in the electric quantum limit. The quantum results are more readily acceptable and give a band bending of 140 meV, a mean carrier distance from the surface of 30 AA and an accumulation layer thickness of 80 AA.