The addition of a small percent of nitrogen to GaAs causes a large reduction of the band gap energy and a tensile strain within the lattice. The further addition of H at 300 C causes a recovery of the band gap of the N-free GaAs host. Concomitantly, tensile strain turns into compressive strain. Upon reduction of hydrogenation temperature, high-resolution x-ray diffraction studies show now a remarkable increase of compressive strain, while photoluminescence measurements show that the recovered band gap energy of GaAs …