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 wit h 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 resul ts are consistent with a perturbation of the GaSe band structure due t o carrier confinement. resulting in a widening of the forbidden gap. A second harmonic signal generated with the 1064nm line of a mode-locke d Nd:YAG laser was observed in particles which had been spin-coated on to a glass substrate from solution.