The article doesn't explicitly say whether it is bulk Gallium Arsenide, or a quantum-well structure based on a sandwich of Gallium Arsenide and its crystalline alloys. Bizarre excitonic behavior in a quantum-well doesn't surprise me much, however in bulk it would be a remarkable phenomenon.

Also, droplets in physics (whether in the water, or in the nucleus) exhibit 'surface tension' effects - basically energy dynamics between volume and surface area. If that was the case here it would make this phenomenon very interesting indeed.