On a possibility to form small crystallites of layered gallium selenide via ultrasonic treatment

A powder as well as single crystals of layered gallium selenide (GaSe) in methanol were sonicated under ambient conditions. After filtration or centrifugation we obtained a mixture which contained particles with diameters less than 30 nm. The crystallites have Seen characterized by optical absorption spectroscopy. The spectra of crystallites with a diameter of 20 nm and less turned out to be blue shifted. These results are consistent with a perturbation of the GaSe band structure due to carrier confinement. resulting in a widening of the forbidden gap. A second harmonic signal generated with the 1064nm line of a mode-locked Nd:YAG laser was observed in particles which had been spin-coated onto a glass substrate from solution.