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Abstract
Optical properties of GaAs1−x N x alloys grown by molecular beam epitaxy using GaAs (001) as the substrate have been studied. These include photoluminescence (PL), cathodoluminescence (CL), photocurrent and photomemory effects. The low-temperature (77 K) PL characteristics were measured on samples with 0–0.105% N content. The wide emission band indicates the defective nature of the materials. The widening of the band for materials with increasing nitrogen concentration also suggested that the concentration of defect states in these materials dramatically increased with increasing nitrogen content. The PL and CL spectra for GaAs1−x N x layer 1854 did not show identical characteristics. Some layers showed a very sharp fall in photocurrent at low temperatures, indicating a very sharp photoquenching and an interaction between antisite, interstitial and vacancy defects. The photomemory effect, which causes photoquenching and the transition from the EL2 to the EL2∗ metastable state, was strongly influenced by the optical exposure and thermal history of the sample.
Acknowledgements
The authors wish to thank Dr Jaime Freitas for fruitful discussions. The research is supported by the US Air Force Office of Scientific Research under grant F49620-99-1-0182.
