Controlled synthesis of CdS nanobelts and the study of their cathodoluminescence

Cadmium sulfide nanobelts were synthesized on an Au-capped Si substrate via chemical vapor deposition by annealing CdS powder at 860 °C. Two types of nanobelts were found. While both types grew towards [101¯0], only one type had Au particle at its tip. Room-temperature cathodoluminescence (CL) was performed on the nanobelts which were prepared between 840 and 1060 °C. Each CL spectrum exhibited two peaks. The maximum band edge emission (BEE) was found at 510 nm in all spectra while that of the deep level emission (DLE) was located between 706 to 756 nm. The ratio of intensity of BEE to that of DLE increased with increasing annealing temperature. The variation of the DLE intensity in the samples was due to the variation of defect density. A blue shift up to 49 nm was detected for DLE as the annealing temperature was increased by 160 °C. Such a shift is due to the presence of more than one type of defects in these CdS nanobelts.