Nitrogen-induced enhancement of the free electron concentration in sulfur implanted GaNxAs1−x

We have achieved a large increase of the activation efficiency of sulfur atoms implanted into GaNxAs1−x thin films. For thin films with only 0.8% N content, we find a maximum free electron concentration of >6×1018 cm−3 for implanted S concentration higher than 1019 cm−3, about 20 times larger than that in semi-insulating GaAs implanted and annealed under the same conditions. This large increase of the free electron concentration can be quantitatively explained with the recently developed band anticrossing model.