Selective disposition of nanocarriers into target tissue is an essential issue in drug delivery. Critical size of nanocarriers (∼150 nm) discriminating the permeability into normal and tumor tissues was determined by the use of size-tunable, polyion complex hollow vesicles (PICsome) as a ruler.

InGaN-based light-emitting diodes (LEDs) have been widely accepted as highly efficient light sources capable of replacing incandescent bulbs. However, applications of InGaN LEDs are limited to small devices because their fabrication process involves expensive epitaxial growth of InGaN by metalorganic vapor phase epitaxy on single-crystal wafers. If we can utilize a low-cost epitaxial growth process, such as sputtering on large-area substrates, we can fabricate large-area InGaN light-emitting displays. Here, we report the growth of GaN (0001) and InGaN (0001) films on amorphous SiO2 by pulsed sputtering deposition. We found that using multilayer graphene buffer layers allows the growth of highly c-axis-oriented GaN films even on amorphous substrates. We fabricated red, green, and blue InGaN LEDs and confirmed their successful operation. This successful fabrication of full-color InGaN LEDs on amorphous substrates by sputtering indicates that the technique is quite promising for future large-area light-emitting displays on amorphous substrates.

We have grown GaN on atomically flat ZnO (000-1) substrates at room temperature with pulsed laser deposition (PLD). We have found that atomically flat surfaces of ZnO (000-1) substrates with a clear step and terrace structure have been obtained by annealing in a box made of ceramic ZnO. We have also found that GaN grows epitaxially even at room temperature on the step and terrace ZnO surface. Reflection high energy electron diffraction (RHEED) observations have revealed that the GaN film grows in the layer by layer mode from the early stage of the film growth. X-ray reflectivity measurements have revealed that the heterointerface between GaN and ZnO is quite abrupt and its roughness is less than 0.5 nm.

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The authors have grown high-quality m-plane GaN (11¯00) films on ZnO (11¯00) substrates using pulsed laser deposition. They have found that annealing in a box made of ceramic ZnO improves the surface morphology of m-plane ZnO substrates and have succeeded in the layer-by-layer growth of m-plane GaN on the annealed ZnO substrates even at room temperature (RT). X-ray diffraction reveals that high crystalline quality m-plane GaN grows on the RT buffer layer at 700°C. The 300-nm-thick m-plane GaN film grown on the ZnO substrate contains the residual strains because the lattice mismatches between them are quite small. The relationship of in-plane and out-of-plane strains is consistent with the calculation using the elastic constants.