CHEMICAL BEAM EPITAXY GROWTH AND CHARACTERIZATION OF GANAS GAAS/

A GaNAs layer has been grown on a GaAs substrate using chemical beam e pitaxy (CBE) with a radio frequency (RF) radical nitrogen source for t he first time. The nitrogen (N) composition was well-controlled by the N-2 flow rate and was increased up to 2.7%, maintaining a good crysta l quality. The maximum N composition was estimated to be 20% by a seco ndary ion mass spectroscopy (SIMS) measurement. The N composition esti mated from both X-ray diffraction measurements and SIMS measurements w ere in good agreement. This shows that the N composition can simply be determined by X-ray diffraction measurements. The optical absorption measurement of the grown GaNAs was also carried out. The bandgap bowin g parameter of GaNAs was found to be not a constant and varied between 15-23 eV for N<2.7%. An empirical expression of bandgap vs. compositi on was obtained for a N composition below 3%.