An InGaN/GaN p-i-n solar cell inserted with a 5-nm low-temperature(LT)GaN interlayer between the p-GaN cap layer and the InGaN i-layer is grown on a c-plane sapphire substrate by metal organic chemical vapor deposition.The effects of the LT GaN interlayer on the performance of the InGaN/GaN solar cells are investigated.It is found that the LT-GaN interlayer prevents the extension of threading dislocations from the InGaN layer to the p-GaN layer and improves the crystal quality of both the p-GaN cap layer and the InGaN i-layer,ultimately leading to an increasing external quantum efficiency and photocurrent density of the InGaN/GaN solar cells.
The light extraction efficiencies have been calculated for various InGaN/GaN multiple quantum well nanostructure light-emitting diodes including nanopillar, nanorough of P-CaN surface, coreshell and nano-interlayer structure. From the calculated results we can see that the light extraction efficiency is remarkably improved in the nanostructures, especially those with an InGaN or AlCaN nano-interlayer. With a 420-nm luminescence wavelength, the light extraction efficiency can reach as high as 65% for the InGaN or AlGaN nano-interlayer structure with appropriate In or Al content while only 26% for the planar structure.
