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Photoluminescence and optically detected magnetic resonance techniques are utilized to study defect properties of GaNP and GaNAs alloys subjected to post-growth hydrogenation by low-energy sub-threshold ion beam irradiation. It is found that in GaNP H incorporation leads to activation of new defects, which has a Ga interstitial (Gai) atom at its core and may also involve a H atom as a partner. The observed activation critically depends on the presence of N in the alloy, as it does not occur in GaP with a low level of N doping. In sharp contrast, in GaNAs hydrogen is found to efficiently passivate Gai-related defects present in the as-grown material. A possible mechanism responsible for the observed difference in the H behavior in GaNP and GaNAs is discussed. [ABSTRACT FROM AUTHOR]

Wereport on identification and control of important nonradiative recombinationcenters in GaNP coaxial nanowires (NWs) grown on Si substrates inan effort to significantly increase light emitting efficiency of thesenovel nanostructures promising for a wide variety of optoelectronicand photonic applications. A point defect complex, labeled as DD1and consisting of a P atom with a neighboring partner aligned alonga crystallographic ⟨111⟩ axis, is identified by opticallydetected magnetic resonance as a dominant nonradiative recombinationcenter that resides mainly on the surface of the NWs and partly atthe heterointerfaces. The formation of DD1 is found to be promotedby the presence of nitrogen and can be suppressed by reducing thestrain between the core and shell layers, as well as by protectingthe optically active shell by an outer passivating shell. Growth modesemployed during the NW growth are shown to play a role. On the basisof these results, we identify the GaP/GaNyP1–y/GaNxP1–x(x< y) core/shell/shell NW structure, where theGaNyP1–yinner shell with the highest nitrogen content serves as an activelight-emitting layer, as the optimized and promising design for efficientlight emitters based on GaNP NWs. [ABSTRACT FROM AUTHOR]

The factors contributing to the band gap bowing of the dilute nitride GaNP are analyzed. It is found that the band gap bowing is due to two factors. One is the coupling interaction between the N level and the Γ conduction band minimum of GaP. The other is the coupling interaction between the N level and the X conduction band minimum of GaP. We also estimate the band gap reduction due to each factor. It is found that the band gap bowing is mainly due to the coupling interaction between the N level and the Γ conduction band minimum of GaP. [ABSTRACT FROM AUTHOR]

GaN-based ultraviolet (UV) LEDs are widely used in numerous applications, including white light pump sources and high-density optical data storage. However, one notorious issue is low hole injection rate in p-type transport layer due to poorly activated holes and spontaneous polarization, giving rise to insufficient light emission efficiency. Therefore, improving hole injection rate is a key step towards high performance UV-LEDs. Here, we report a new method of suppressing spontaneous polarization in p-type region to augment light output of UV-LEDs. This was achieved by simply passivating graphene oxide (GO) on top of the fully fabricated LED. The dipole layer formed by the passivated GO enhanced hole injection rate by suppressing spontaneous polarization in p-type region. The homogeneity of electroluminescence intensity in active layers was improved due to band filling effect. As a consequence, the light output was enhanced by 60% in linear current region. Our simple approach of suppressing spontaneous polarization of p-GaN using GO passivation disrupts the current state of the art technology and will be useful for high-efficiency UV-LED technology. [ABSTRACT FROM AUTHOR]