InGaN/GaN multiple-quantum-well light-emitting-diode structures utilizing tunnel contact junctions grown by metalorganic chemical vapor deposition have been demonstrated. The p+/n+ GaN tunnel junctions are located in the upper cladding layers of conventional devices, allowing n-type GaN instead of p-type GaN as a top contact layer. Thus, metal ohmic contacts are done at the same time on the top and the lower contact layers. The reverse-biased tunnel contact junction provides lateral current spreading without semitransparent electrode and spatially uniform luminescence exhibiting an improved radiative efficiency. The tunnel contact junction is shown to be an effective method to make possible hole injection via a lateral electron current, with only a small penalty in voltage drop compared to conventional devices.

The role of two-step low-temperature GaN (LT-GaN) layers was investigated by cathodoluminescence, high resolution double crystal X-ray diffraction, transmission electron microscopy, atomic force microscopy, and current-voltage measurements. It was shown that the introduction of the LT-GaN layer prevents In from evaporating from InGaN during the high-temperature growth of p-GaN. The trasmission electron microscopic (TEM) results showed that the LT-GaN hampers dislocation propagation from the InGaN active layer into the p-GaN, leading to reduction in the dislocation density in the p-GaN. The use of the two-step LT-GaN resulted in an increase in the output power of light-emitting diodes and a decrease in the operating forward voltage.

We have investigated the characteristics of InGaN/GaN blue light-emitting diodes (LEDs) with a Si d-doped GaN contact layer. The Si d-doping of the GaN contact layer in the devices could enhance the Si doping concentration and improve the lateral conductivity in the GaN : Si contact layer without cracking. The operating voltage and dynamic resistance of LEDs with a Si d-doped GaN contact layer were 3.65 V and 27 W at 20 mA, respectively. The operating voltage and dynamic resistance of conventional LEDs with a uniformly doped GaN : Si contact layer were 3.94 V and 32.3 W at 20 mA, respectively. Also, the leakage currents at a reverse bias of --10 V were 2.8 mA for d-doped LEDs and 29 mA for uniformly doped LEDs. However, emission properties such as electroluminescence spectra and output power were not largely affected by utilizing a d-doped GaN:Si contact layer in the devices.

Objectives In this study, we seek to find out the mothers' perception of parental education experience and discover the subjectivity and characteristics of parental education experience to contribute to vitalization of parental education as a follow-up study. Methods To this end, a total of 140 statements were derived through literature analysis and in-depth interviews for a total of 32 days from July 28 to August 30, 2022, and 32 mothers with early childhood children were selected as the P sample and Q classification was conducted. did The collected data were analyzed using the PC-QUANL Program. Results As a result of the study, there were four types of parental education experiences for mothers with early childhood children, Type 1 was “parent education priority type”, Type 2 felt the need for parental education after parental education experience, Type 3 was “relationship-centered type”, and Type 4 was more “linear” emphasizing parental change than parental education experience. Conclusions Through the results of this study, the subjective perception structure of mothers with early childhood children was classified and confirmed, and it is expected to be used as basic data to increase access to parent education for mothers with early childhood children.

In the field of organic light emitting diodes (OLEDs), organo-boron based thermally activated delayed fluorescence (TADF) emitters have reached great achievement. However, it is still challenging to achieve pure blue color (CIE y < 0.20) along with high efficiencies. To overcome these hurdles, hyperfluorescence (HF) suggest a key strategy in future OLED applications. Here, we report two TADF materials, pMDBA-DI and mMDBA-DI. Further, a pure blue multi resonance type tert-butyl substituted fluorescence emitter, t-Bu-ν-DABNA was also synthesized. Among our synthesized TADF materials based pure blue HF devices, mMDBA-DI as TADF sensitized host with t-Bu-ν-DABNA fluorescence emitter exhibited a high external quantum efficiency of 40.7% (Lambertian assumption) along with narrow emission with full width at half maximum of 19 nm (CIE y = 0.15). Moreover, we analyzed that such high device efficiency is mainly attributed to the high orientation factor, enhanced photoluminescence quantum yield, and a good TADF characteristic of t-Bu-ν-DABNA with high Förster resonance energy transfer.