Tuning of the electron effective mass and exciton wavefunction size in GaAs1−xNx

The electron effective mass, View the MathML source, and exciton radius, rexc, have been derived in View the MathML source by magneto-photoluminescence measurements. With increasing nitrogen concentration, View the MathML source and rexc undergo a rapid increase and squeezing, respectively, already for x≈0.1%. Furthermore, in a hydrogen-irradiated GaAs1−xNx sample, the band gap widening induced by H maps on a profound modification of the conduction band. View the MathML source decreases (increases) with increasing H dose, until the GaAs value is obtained. First-principle calculations show that the formation of a specific N–H2 dihydrogen complex leads to the removal of the electron localization caused by N incorporation in GaAs.