Nanomaterials @ Interfaces Research Group

We have studied the microstructure and morphology evolution in PbSe films chemically deposited on GaAs(100) substrates. The films consisted of a single phase of nanocrystalline rocksalt PbSe. The deposition temperature was found to be an important parameter which strongly influences the film morphology. A gradual transition to strong (111) texture was obtained with increasing deposition temperature, accompanied by a significant increase in crystallite size. Transmission electron microscopy (TEM) cross-sections showed two distinct regions. A layer of small, rounded crystals near the GaAs/PbSe interface above which a second region composed of columnar, <111> oriented crystallites was observed. High resolution TEM and Fourier analysis showed that the first layer of crystallites are in epitaxial registry with the GaAs substrate, in spite of the large (8%) lattice mismatch and the presence of a thin, amorphous interfacial layer.