Quaternary AlxInyGa1−x−yN layers deposited by pulsed metal-organic vapor-phase epitaxy for high efficiency light emission

Quaternary AlInGaN quantum wells in GaN barriers were grown by metal-organic vapor-phase epitaxy. Changing to a growth sequence with pulsed metal-organic supply leads to structures with enhanced photoluminescence efficiencies. The amount of material was varied, resulting in AlInGaN layer thicknesses between nominally 1.5 and 10 nm.We have analyzed the material properties by X-ray diffraction (XRD) as well as photoluminescence (PL) spectroscopy. The observed XRD-spectra and the PL intensity show the high quality of the deposited material.By analyzing the PL spectra, we have found an energy shift of the resonance lines from 2.65 to 3.33 eV with decreasing well thickness. We attribute this shift mainly to the presence of internal electric fields in the AlInGaN/GaN heterostructures. Power-dependent and time-resolved PL experiments confirm this observation. By properly adjusting the material composition, we could achieve polarization field compensation of the quaternary QW structures. Also, first luminescence experiments on ternary InGaN QW embedded in quaternary barrier material were performed.