"...The team is exploring several variations on the process, including the use of other low-melting-point metal alloys."

Let's hope so, as this process, as it stands, will go nowhere fast, due to its dependence upon a very expensive rare earth in short supply, that --in an of itself-- presents some very high environmental costs, which I doubt have been factored into the calculation of the "greenness" of this process.

Perhaps some serendipitous discovery of a cheap, abundant and less environmentally damaging "liquid metal" can be found, but until then, this discovery is only an interesting experimental demonstration.

The article didn't say if the liquid gallium was consumed in any way (including evaporation) by this process. If not, and if evaporation of the liquid metal could be entirely avoided, then perhaps the liquid metal could be mercury. Not at all environmentally friendly, but if it is more like a catalyst than a consumed ingredient, then perhaps some type of reactor vessel could be used to contain it properly. While very environmentally dangerous, it is not nearly as dangerous as many of the chemicals used to create various semiconductors and that industry seems to be able to prevent the release of these very noxious chemicals.

Let's hope so, as this process, as it stands, will go nowhere fast, due to its dependence upon a very expensive rare earth in short supply

Gallium is not a "rare earth".
Gallium is not even particularly rare (which is different from being a "rare earth") - it is more plentiful in earth's crust than lead or tin, for example.
Furthermore gallium is not consumed in this process.

The small crystal size is more likely to be a problem than the gallium is.

Let's hope so, as this process, as it stands, will go nowhere fast, due to its dependence upon a very expensive rare earth in short supply

Gallium is not a "rare earth".
Gallium is not even particularly rare (which is different from being a "rare earth") - it is more plentiful in earth's crust than lead or tin, for example.
Furthermore gallium is not consumed in this process.

The small crystal size is more likely to be a problem than the gallium is.

You are correct, it isn't a rare earth. I was thinking of Indium, for some reason, when I wrote that.

Still, its relative abundance is not so vast, nor is it so readily available, that this might prove an impediment to this process on an industrial scale.