Effects of weak ordering of InGaPN

The effect of weak ordering on InGaPNGaAs heterostructure grown by gas source molecular-beam epitaxy is quantitatively studied by room-temperature Raman, photoluminescence (PL), and photoreflectance spectroscopy in this work. The PL intensity decreases rapidly as the nitrogen concentration increases, implying that more nonradiative centers are generated by the ordering effect and the degradation of the samples. The band gap of InGaPN decreases dramatically as the nitrogen is incorporated. The Raman modes of InGaPN between 130 and 1000 cm-1 are analyzed. Polarized Raman spectra reveal that the InGaPN layers become more ordered as more nitrogen is incorporated. A broad Raman structure that appeared around 730 cm-1 is attributed to an InGaN-like LO-phonon mode. The transition of the crystal structure from the zinc blende to CuPt structure and the formation of GaN clusters are responsible for the ordering effect in the InGaPN layer.