Spectroscopic investigation in high magnetic fields of the dilute nitride GaAsN

As a member of the dilute nitride family, GaAsN is a highly interesting material system for many application purposes such as LEDs, lasers, solar cells, and infrared photodetectors because of the tuning possibility of these devices by the variation of the nitrogen content. An accurate description of this new material system involves the knowledge of the band structure and in particular the effective mass. Motivated by the inconsistency of previous results (e.g. [1, 2]), which can be traced down to the particular investigation method, we use several spectroscopy techniques in a series of GaAsN epilayers with 0.1 - 1 % of nitrogen. Cyclotron resonance spectroscopy, being the most direct method, reveals that the cyclotron resonance frequency is not significantly affected by the nitrogen doping and thus the effective mass. Magneto-photoluminescence, on the other hand, stems from several transitions, which are not resolved spectrally, but identified in time-resolved measurements. We discuss the different behaviour of these transitions in magnetic fields up to 7 T (static) and 41 T (pulsed). We find that the diamagnetic shift of the electron-to-carbon impurity transition cannot be always applied reliably to determine the electron effective mass. However, this method has been employed frequently in previous studies, which may explain the contradictory values reported in the literature.

[1] K. Alberi et al. Phys. Rev. Lett. 110, 156405 (2013)
[2] F. Masia et al Phys. Rev. B 73, 073201 (2006)