It is said to have potential for optical applications but the exploitation of this potential has been limited by the ability to readily grow single crystals Gallium selenide crystals show great promise as a nonlinear optical material and as a photoconductor. Non-linear optical materials are used in the frequency conversion of laser light. Frequency conversion involves the shifting of the wavelength of a monochromatic source of light, usually laser light, to a higher or lower wavelength of light that cannot be produced from a conventional laser source.
Several methods of frequency conversion using non-linear optical materials exist. Second harmonic generation leads to doubling of the frequency of infrared carbon dioxide lasers. In optical parametric generation, the wavelength of light is doubled. Near-infrared solid-state lasers are usually used in optical parametric generations.
One original problem with using gallium selenide in optics is that it is easily broken along cleavage lines and thus it can be hard to cut for practical application. It has been found, however, that doping the crystals with indium greatly enhances their structural strength and makes their application much more practical. There remain, however, difficulties with crystal growth that must be overcome before gallium selenide crystals may become more widely used in optics.
Single layers of gallium selenide are dynamically stable two-dimensional semiconductors, in which the valence band has an inverted Mexican-hat shape, leading to a Lifshitz transition as the hole-doping is increased.
The integration of gallium selenide into electronic devices has been hindered by its air sensitivity. Several approaches have been developed to encapsulate GaSe mono- and few-layers, leading to improved chemical stability and electronic mobility.