Heteroepitaxy of Hexagonal ZnS Thin Films Directly on Si (111)

Epitaxial Wurtzite ZnS (W-ZnS) films were grown directly on Si (111) at temperatures as high as 800°C by pulsed laser deposition. A detailed deconvolution method was used to discriminate the ZnS reflection from superimposed peaks overlapped by both ZnS and Si peaks in X-ray measurement. From the peak deconvolution, the rocking full width at half maximum and lattice constant of the ZnS film were determined to be 0.28° and 6.26 Å, respectively. A tilt between W-ZnS and Si was observed and the tilt angle decreased with increasing growth temperature. The W-ZnS (0001) film on Si (111) showed the epitaxial relationship of Si [220]//ZnS[101̄5]. An X-ray diffraction scan along the L direction in reciprocal space and a high-resolution transmission electron microscopy image revealed that the W-ZnS film partially had stacking fault domains in the hexagonal phase. Free excitonic emission from the W-ZnS film was observed at 4 K.