Relation between N-H complexes and electrical properties of GaAsN determined by H implantation

We investigated the relation between N-H complexes and the electrical properties of GaAsN, which is a potential material for fabricating super-high-efficiency multi-junction tandem solar cells. In order to separate the effect of other residual carrier such as carbon in a GaAsN film on the electrical properties, hydrogen (H) ions were implanted into GaAsN grown by chemical beam epitaxy (CBE) and then rapid thermal annealing from 250 to 650 °C was carried out. Two N-H complexes related to local vibrational modes (LVMs) in GaAsN were observed at 3098 and 3125 cm−1. With an increasing annealing temperature, the integrated peak intensity of the 3098 cm−1 peak (I3098) decreased, while that of the 3125 cm−1 peak (I3125) increased. This indicates that N-H complexes related to the 3125 cm−1 peak are thermally more stable than those related to the other peak. The hole concentrations and mobilities exhibited an increasing trend until an annealing temperature of 550 °C was reached. Their increases are attributed to the removal of donor-type defects. It is suggested that the N-H complexes related to the 3098 cm−1 peak are electrically active, while those giving the 3125 cm−1 peak are inactive.