Molecular beam epitaxy of quaternary semiconductor alloy GaNAsBi

New semiconductor GaN_yAs_1-x-yBi_x alloy with the GaBi molar fraction (x) up to 4.0% and the GaN molar fraction (y) up to 8.0% has been grown by molecular beam epitaxy. Incorporation of Bi and N atoms into epilayers was confirmed by Rutherford backscattering spectroscopy and secondary ion mass spectroscopy. To achieve Bi incorporation, As flux was adjusted in a limited range on the brink of As shortage on the growing surface at a low substrate temperature. The lattice constant determined by X-ray diffraction increased with the Bi supply, and it decreased with increasing N supply. The alloy is suitable to realize both a temperature-insensitive bandgap in the waveband of optical fiber communication and the lattice constant matched to that of GaAs.