The use of localized surface plasmon (LSP) interaction for significantly enhancing InGaN absorption near its band edge and the overall efficiency of an InGaN-based solar cell by embedding Ag nanoparticles (NPs) in the InGaN absorbing layer is numerically demonstrated. The generation of LSP resonance on the embedded Ag NPs and the NP scattering can produce a field distribution in the InGaN layer for enhancing absorption. It is shown that the embedded Ag NPs do not significantly affect the transport of the photo-generated carriers. The distortion of static electrical stream lines in the solar cell due to the embedded Ag NP leads to a decrease of photocurrent by only a few percents. Based on the material parameter values we use, unless the surface recombination velocity at the interface between the Ag NP and surrounding InGaN is extremely high, Ag NP embedment in the absorbing layer of an InGaN-based solar cell can enhance its efficiency by up to 27%. Such an increase is significantly larger than that achieved by depositing metal NP on the top surface of a solar cell.

Articles you may be interested inIn situ X-ray investigation of changing barrier growth temperatures on InGaN single quantum wells in metalorganic vapor phase epitaxy J. Appl. Phys. 115, 094906 (2014); 10.1063/1.4867640 Metal-organic chemical vapor deposition growth of InGaN/GaN high power green light emitting diode: Effects of InGaN well protection and electron reservoir layer J. Appl. Phys. 102, 053519 (2007); 10.1063/1.2776218 High quality InN/GaN heterostructures grown by migration enhanced metalorganic chemical vapor depositionInGaN layers have been grown on ͑0001͒ ZnO substrates by metalorganic chemical vapor deposition utilizing a low temperature grown thin GaN buffer. Good quality InGaN films with a wide range of In composition were confirmed by high-resolution x-ray diffraction. Even at high indium concentrations no In droplets and phase separation appeared, possibly due to coherent growth of InGaN on ZnO. Photoluminescence showed broad InGaN-related emissions with peak energy lower than the calculated InGaN band gap, possibly due to Zn/O impurities diffused into InGaN from the ZnO substrate. An activation energy of 59 meV for the InGaN epilayer is determined.

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In this work, ZnO has been investigated as a substrate technology for GaN-based devices due to its close lattice match, stacking order match, and similar thermal expansion coefficient. Since MOCVD is the dominant growth technology for GaN-based materials and devices, there is a need to more fully explore this technique for ZnO substrates. Our aim is to grow low defect density GaN for efficient phosphor free white emitters. However, there are a number of issues that need to be addressed for the MOCVD growth of GaN on ZnO. The thermal stability of the ZnO substrate, out-diffusion of Zn from the ZnO into the GaN, and H 2 back etching into the substrate can cause growth of poor quality GaN. Cracks and pinholes were seen in the epilayers, leading to the epi-layer peeling off in some instances. These issues were addressed by the use of H 2 free growth and multiple buffer layers to remove the cracking and reduce the pinholes allowing for a high quality GaN growth on ZnO substrate.

The metalorganic chemical vapor deposition (MOCVD) growth of GaN based materials on ZnO substrates has numerous technical issues that need to be investigated and resolved. These include the thermal stability of ZnO, out‐diffusion of Zn/O from the ZnO into the epilayers, and H2 back etching into the ZnO all of which can cause poor film quality. Cracks and pinholes were seen in the epilayers, leading to the epilayer peeling off. In this study, good quality InGaN films with a wide range of indium incorporation have been grown on (0001) ZnO substrates by MOCVD. No indium droplets and phase separation were observed even at high indium concentrations. The optical microscopy and field‐emission scanning electron microscopy revealed a mirror‐like InGaN surface with no evidence of indium droplets on the surface. Photoluminescence (PL) showed broad InGaN‐related emissions with peak energy lower than the calculated InGaN band gap, possibly due to Zn/O impurities diffused into InGaN from the ZnO substrate. More recently, Al2O3 coated ZnO substrates have been employed for growth to limit Zn diffusion as well as assist epilayer growth. HRXRD result shows that a single crystal InGaN film has been successfully grown on an annealed Al2O3 coated ZnO substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)