A multilayer barrier structure composed of silicon nitride, silicon oxide, and encapsulated parylene on a polycarbonate substrate has been investigated for flexible electronic applications. The organic buffer is commonly used as the smoothing, strengthening and defect‐decoupling layer. However, a lateral leakage problem was observed in the organic interlayer, and resulted in increased permeation and poor adhesion between organic and inorganic layers. It was found that an encapsulated, thermal‐treated parylene interlayer can be used to efficiently reduce the water vapor and oxygen permeation. After 75 d, the water vapor transmission rate (WVTR) can reach 2.5 × 10−7 (g · m−2) d−1, as calculated by the calcium test. After being flexed for 5 000 times, the WVTR value almost keeps around 2.1 × 10−6 (g · m−2) d−1. The performance of the proposed multilayer barrier structure has a high potential for flexible solar cell and organic light‐emitting diode applications.magnified image

We have successfully synthesized vertically aligned ZnO nanotube arrays by metalorganic chemical vapor deposition. Since no metal catalysts are used in this work, the growth process of ZnO nanotube arrays does not follow a vapor-liquid-solid mechanism but a self-catalyzed growth mechanism. X-ray diffraction results show that the nanotubes have ZnO hexagonal wurizite structures and only the ZnO (0002) peak can be seen. The rocking curve also shows a full width at half-maximum value of similar to 1625 arc second. A 6-fold symmetry in phi-scan data is also observed, indicating in-plane alignment of ZnO nanotube arrays. Room temperature photoluminescence results present a high optical quality and nearly defect-free crystal structure of ZnO nanotube at-rays. Moreover, the high near-band edge emission to deep level emission intensity ratio (I(NBE)/I(DLE)) of 2050 is obtained

Silicon oxide (SiO x ) and silicon nitride (SiN x ) thin films have been deposited onto flexible polycarbonate (PC) substrates using plasma-enhanced (PE)CVD for transparent barrier applications. Comparing the internal stress, optical transparency, surface roughness, and impermeability results, a multilayer composed of parylene/SiO x /SiN x ...parylene/SiO x /SiN x (PON...PON) is deposited on PC substrates and the optimum thicknesses of the SiN x , SiO x , and parylene layers is determined. Under optimum conditions, the water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) of SiO x (50 nm)/SiN x (50 nm) barrier coatings on PC at 80°C decreases to values near 0.01 g m -2 per day and 0.1 cm 3 m -2 per day, respectively. To further reduce the WVTR and OTR values, parylene layers are used as a smoothing, defect-decoupling, and protective medium in the multilayer. It has been found that organic light-emitting diodes capped with double PON layers show no dark spots and exhibit better emissions than single PON layers after 100 h at 25°C, and 40 % relative humidity.

ZnO nanowall networks with a honeycomblike pattern on GaN/sapphire substrates were deposited by metalorganic chemical vapor deposition (MOCVD) without using any metal catalysts. The effects of growth temperature and VI/II ratio on the surface morphology and optical properties of ZnO nanowall networks were investigated by scanning electron microscopy (SEM) and photoluminescence (PL) analysis. The SEM image obtained shows a prominent nanowall-network structure when the growth temperature is higher than 550 C. The wall width and network size of ZnO nanowall-network structures grown by MOCVD were found to change depending on DEZn flow rate. The surface morphology of ZnO structures was observed at different time intervals from 10 to 40 min to investigate the formation mechanism of ZnO nanowall networks. The roomtemperature PL measurement of ZnO nanostructures grown on GaN/sapphire substrates shows high-intensity ultraviolet peaks at 385 nm without any ''green peak''. The PL spectrum suggests that the quantum confinement effects are caused by the nanostructure of ZnO.

ZnO deposited on sapphire substrate is investigated as a function of growth temperature in the range 350 similar to 650 degrees C. The surface morphology of ZnO structures changes significantly with increasing growth temperature. Though ZnO crystal quality and optical property can be improved under high growth temperature, ZnO is inclined to form nanostructures. Therefore, we propose the repeated growing and annealing (RGA) growth mode as a reliable and reproducible way for the growth of ZnO film. The RGA growth mode is performed at a growth temperature of 450 degrees C for 8 min, an anneal temperature of 650 degrees C for 20 min, and repeatedly switched between growing and annealing. Meanwhile, we compare the effects of annealing under Ar, N(2), and O(2), and found that a low resistivity of 3.4 x 10(-3) Omega cm and a high mobility of 85.2 cm(2) V(-1) s(-1) can be obtained annealing under N(2)