Solution Transformation of Metal Thin Films to II-VI Semiconductor Films

Abstract

ABSTRACTThe low temperature solution based transformation of silver metal layers to II-VI materials is investigated as an alternative mechanism for forming semiconductor thin films. This metal to semiconductor conversion has been demonstrated with the solution based sulfurization and ion exchange of silver nanoparticles, but not to our knowledge on thin films. Starting with metal films is attractive because they may be scalably deposited on many substrates through evaporation or electro- and electroless plating. The metal to II-VI transformation is challenging in films because diffusion occurs directionally and because the ∼40% increase in lattice expansion may cause debonding. Silver films were deposited on glass with Ti adhesion layers and successfully transformed to well-adhered CdS and MnS films at ≤ 60 ºC. The II-VI compounds were confirmed by XRD and shown to be polycrystalline with SEM. Electrical conductivities, bandgaps, and optical absorption spectra were measured. These results demonstrate that solution based sulfurization and ion-exchange is a viable mechanism for forming II-VI semiconductor thin films with good conductivities from metal films at low temperatures.