The development of a full-color micro-display at the Industrial Technology Research Institute (ITRI) was reviewed in this study. The blue microdisplay with 960 × 540 pixel arrays and 1984 PPI resolution is demonstrated on a CMOS active matrix addressing circuit. Different methods of fabricating such a micro-panel are developed to overcome the limitation in mass transfer. For the device size ranging from 5-100 micrometers, lowcurrent external quantum efficiency of 10%-14% can be obtained. To achieve a full-color scheme, we adapt color-conversion layer design and use colloidal quantum dots as the illuminating material. A full-color array on a transparent substrate of 170 PPI resolution was demonstrated with a large-area blue LED backlight. The red and green pixels were fabricated by a photolithography process and had a size of 30 μm. The FWHM of 21 and 28 nm and the quantum yield of 28% and 41% for the green and red pixels, respectively, were measured by a 2D spectroradiometer. With superior color provided by quantum dots, it shows a wide color gamut that can fill 87% of Rec. 2020 color space.

In this paper, an observation of drain current instability on p-GaN gate AlGaN/GaN HEMTs is reported. Contrary to the Schottky gate AlGaN/GaN HEMTs, which show stable and consistent I d -V d curves under different pulsed conditions, the I d -V d curves for p-GaN gate AlGaN/GaN HEMTs show a dispersion in the saturation region under the same pulse conditions, which cannot be explained by the trapping of electrons in the material. A model considering the trapping of holes in the p-GaN gate under different gate and drain biases is proposed to explain this new phenomenon.

Zinc gallate (ZnGaO; ZGO) thin films were employed as the p-type transparent contact layer in deep-ultraviolet AlGaN-based light-emitting diodes (LEDs) to increase light output power. The transmittance of 200-nm-thick ZGO in deep-ultraviolet wavelength (280 nm) was as high as 92.3%. Two different ohmic contact structures, a dot-LED (D-LED; ZGO/dot-ITO/LED) and whole-LED (W-LED; ZGO/ITO/LED), exhibited improved light output power and current spreading compared to a conventional ITO-LED (C-LED). At an injection current of 20 mA, the D-LED and W-LED exhibited 33.7% and 12.3% enhancements in light output power, respectively, compared to the C-LED. The enhanced light output power of the D-LED can be attributed to an improvement in current spreading and enhanced light-extracting efficiency achieved by introducing ZGO/dot-ITO.

No abstract

This work demonstrated a-Si:H thin-film solar cells with backside TiO(2)/ SiO(2) distributed Bragg reflectors (DBRs) for applications involving building-integrated photovoltaics (BIPVs). Selectively transparent solar cells are formed by adjusting the positions of the DBR stop bands to allow the transmission of certain parts of light through the solar cells. Measurement and simulation results indicate that the transmission of blue light (430 ~500 nm) with the combination of three DBR mirrors has the highest increase in conversion efficiency.