Articles you may be interested inEffect of RuCoCr-oxide intermediate layers on the growth, microstructure, and recording performance of CoCrPt -SiO 2 perpendicular recording media Two-step-deposited Ru layers of 20 nm have been employed as an underlayer for CoCrPt-SiO 2 perpendicular magnetic recording media. The bottom Ru layer of 10 nm is deposited at 3 mTorr for good texture of hcp ͑0002͒ and the top Ru layer of 10 nm is deposited at various conditions. Sputtering power and Ar pressure are variables for the top Ru layer deposition. As the sputtering pressure of the top Ru layer increases, coercivity ͑H c ͒ of the CoCrPt-SiO 2 layer increases and then saturates or slightly decreases with a further increase of sputter pressure. The H c increase is mainly due to exchange decoupling among grains of CoCrPt. The c-axis alignment of the Ru layer by the two-step deposition method is much improved compared to that of a single-step-deposited Ru layer when the sputtering pressure is higher than 3 mTorr. The grain size of Ru layer is smaller and the grains are well separated by void boundaries when the top Ru sputtering pressure is high. There is a one-to-one relationship between small Ru grains and CoCrPt grains. Although the grain size of CoCrPt layer is small with a good c-axis alignment in the case of lower-pressure-deposited top Ru underlayer, H c is small. The reason will be discussed in terms of grain interconnection.

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For evaluating the effect of light absorption in vertically structured thin film light-emitting diodes (VLEDs), we investigate the dependence of the efficiencies on the several specific parameters including thickness and doping concentration (N(D)) of the n-GaN layer, a design of hetero-structures of the n-GaN layer, and a number of pairs of multi-quantum wells (MQWs). Generally, there is a complementary relation between internal quantum efficiency (IQE) and light extraction efficiency (LEE). However, we confirmed that LEE determined by light absorption is more dominant than IQE in VLED structures with a textured surface, from numerical simulation and experimental results. Effect of light absorption is more prominent in the vertical chip with a textured surface than in that with a flat surface, because a travel length of light extracted from the textured surface is longer. Minimizing light absorption in VLEDs is a key technology for improving light output, and light absorption speaks for the index of enhancement by the general technologies for improving LEE.

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