Abstract
A GaNAs layer has been grown on a GaAs substrate using chemical beam epitaxy (CBE) with a radio frequency (RF) radical nitrogen source for the first time. The nitrogen (N) composition was well-controlled by the N2 flow rate and was increased up to 2.7%, maintaining a good crystal quality. The maximum N composition was estimated to be 20% by a secondary ion mass spectroscopy (SIMS) measurement. The N composition estimated from both X-ray diffraction measurements and SIMS measurements were 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 bowing 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. composition was obtained for a N composition below 3%.