Electrical and physical characterization of the Al2O3/p-GaSb interface for 1%, 5%, 10%, and 22% (NH4)(2)S surface treatments

In this work, the impact of ammonium sulfide ((NH4)(2)S) surface treatment on the electrical passivation of the Al2O3/p-GaSb interface is studied for varying sulfide concentrations. Prior to atomic layer deposition of Al2O3, GaSb surfaces were treated in 1%, 5%, 10%, and 22% (NH4)(2)S solutions for 10 min at 295 K. The smallest stretch-out and flatband voltage shifts coupled with the largest capacitance swing, as indicated by capacitance-voltage (CV) measurements, were obtained for the 1% treatment. The resulting interface defect trap density (D-it) distribution showed a minimum value of 4 x 10(12) cm(-2)eV(-1) at E-v + 0.27 eV. Transmission electron microscopy and atomic force microscopy examination revealed the formation of interfacial layers and increased roughness at the Al2O3/p-GaSb interface of samples treated with 10% and 22% (NH4)(2)S. In combination, these effects degrade the interface quality as reflected in the CV characteristics. (C) 2014 AIP Publishing LLC