A pH adjusted acidic solution of thioacetamide (TAM) was used as a sulfidizing agent to treat long wavelength infrared (LWIR) superlattice surface for the first time. The results were compared against those for ammonium sulfide [(NH4)2S] which have been used earlier for the same purpose. X-ray photoelectron spectroscopy (XPS) results revealed that TAM treatment attains a much pronounced degree of sulfidization on superlattice surface. Electrical measurements on mesa-etched diodes exhibited maximum zero bias dynamic resistance times area (R0A) value of 590 Ω-cm2, approximately a four times improvement compared to (NH4)2S treated diodes. XPS studies revealed the reappearance of detrimental oxides on the TAM treated surface after long term air exposure asserting the need for a suitable capping layer to preserve the quality of the surface. Atomic layer deposition (ALD) was used to cap the TAM treated surface with zinc sulfide (ZnS). Precise deposition of few monolayers of ZnS on TAM treated surface was further studied using XPS to understand the evolution of bond formations at the semiconductor-dielectric interface.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.