What causes the unusual behavior of bandgaps in certain semiconductor materials? This research investigates the composition dependence of the fundamental bandgap of thin, pseudomorphic GaAs1−xNx layers on GaAs substrates. The study combines optical transmission measurements with high-resolution x-ray diffraction to analyze GaAsN layers with varying nitrogen content (0⩽x⩽5%). The study presents a very large set of consistent experimental data. An empirical double exponential composition dependence of the bowing parameter is obtained. This expression accurately describes the measured bandgaps, and allows estimations for higher N incorporations. The bowing parameter reaches 40 eV for very low N incorporations (x≈0.1%), and strongly decreases with increasing N molar fraction. The findings offer insight into the electronic properties of GaAsN, an alloy with potential applications in optoelectronic devices. Understanding this anomalous bowing behavior is critical for optimizing material properties and designing high-performance semiconductor devices.
Published in Applied Physics Letters, this research explores the fundamental properties of a semiconductor material, aligning with the journal’s emphasis on novel materials and devices. The study's use of experimental techniques to characterize the bandgap of GaAsN is consistent with the journal's focus on applied physics and its relevance to technological applications.