Kunook Chung

We fabricated transferable gallium nitride (GaN) thin films and light-emitting diodes (LEDs) using graphene-layered sheets. Heteroepitaxial nitride thin films were grown on graphene layers by using high-density, vertically aligned zinc oxide nanowalls as an intermediate layer. The nitride thin films on graphene layers show excellent optical characteristics at room temperature, such as stimulated emission. As one of the examples for device applications, LEDs that emit strong electroluminescence e

We report the growth of GaN micro-rods and coaxial quantum-well heterostructures on graphene films, together with structural and optical characterization, for applications in flexible optical devices. Graphene films were grown on Cu foil by means of chemical vapor deposition, and used as the substrates for the growth of the GaN micro-rods, which were subsequently transferred onto SiO2/Si substrates. Highly Si-doped, n-type GaN micro-rods were grown on the graphene films using metal–organic chemi

We report the growth of high-quality GaN films on large-size graphene films for visible light-emitting diodes (LEDs). The graphene films were synthesized by chemical vapor deposition and then transferred onto amorphous silica (SiO2) substrates that do not have an epitaxial relationship with GaN. Before growing the high-quality GaN thin films, ZnO nanowalls were grown on the graphene films as an intermediate layer. The structural and optical characteristics of the GaN films were investigated, and

Direct epitaxial growth of inorganic compound semiconductors on lattice-matched single-crystal substrates has provided an important way to fabricate light sources for various applications including lighting, displays and optical communications. Nevertheless, unconventional substrates such as silicon, amorphous glass, plastics, and metals must be used for emerging optoelectronic applications, such as high-speed photonic circuitry and flexible displays. However, high-quality film growth requires g

The epitaxial lateral overgrowth (ELOG) of GaN microdisks on graphene microdots and the fabrication of flexible light-emitting diodes (LEDs) using these microdisks is reported. An ELOG technique with only patterned graphene microdots is used, without any growth mask. The discrete micro-LED arrays are transferred onto Cu foil by a simple lift-off technique, which works reliably under various bending conditions.

Monolithic integration of individually addressable light-emitting diode (LED) color pixels is reported. The integration is enabled by local strain engineering. The use of a nanostructured active region comprising one or more nanopillars allows color tuning across the visible spectrum. In the current work, integration of amber, green, and blue pixels is demonstrated. The nanopillar LEDs exhibit an electrical performance comparable to that of a conventional thin-film LED fabricated on the same waf

Additive color mixing across the visible spectrum was demonstrated from an InGaN based light-emitting diode (LED) pixel comprising red, green, and blue subpixels monolithically integrated and enabled by local strain engineering. The device was fabricated using a top-down approach on a metal-organic chemical vapor deposition-grown sample consisting of a typical LED epitaxial stack. The three color subpixels were defined in a single lithographic step. The device was characterized for its electrica

Single-crystal gallium nitride (GaN) layers were directly grown on centimeter-scale hexagonal boron nitride (h-BN). Using chemical vapor deposition (CVD), centimeter-scale h-BN films were synthesized on a single-crystal Ni(111) and readily transferred onto amorphous fused silica supporting substrates that had no epitaxial relationship with GaN. For growing fully coalescent GaN layers on h-BN, the achievement of high-density crystal growths was a critical growth step because the sp2-bonded h-BN l

Abstract We report the van der Waals integration of micropatterned GaN light-emitting diodes (LEDs) onto foreign graphene films. GaN micro-LEDs were selectively grown on a graphene substrate using a patterned SiO 2 mask, and then the whole device structure was laterally fixed by a polyimide insulator to form a united layer. After device fabrication, the LED/graphene heterostructure device was piled on the foreign graphene layers using a typical wet transfer technique of 2D crystals where the bot

An LED chip containing monolithically integrated red, green, and blue channels was fabricated and characterized. Using local strain engineering in gallium nitride p-i-n nanopillar structures, each color channel emits a distinct color with emission wavelength determined entirely by the diameter of the nanopillar. The crosstalk between color channels is negligible. As a result, individually addressable color channels can be integrated on the same substrate which will be suitable for color-tunable

AlxGa1–xN/GaN disk-in-wire polar nanostructures were fabricated, and their optical properties were studied. Wavelength tuning was observed by locally controlling the strain in each nanopillar via its diameter. The measured wavelength shift was in an excellent agreement with a one-dimensional strain relaxation model considering only the elastic and piezoelectric properties of the material. The inhomogeneous broadening decreases and internal quantum efficiency increases with a decreasing nanopilla

ABSTRACTThis review summarizes research activities on two-dimensional (2D) materials-assisted epitaxy of inorganic semiconductors and their optoelectronic device applications. We presented the overall research related to the growth of epitaxial semiconductor layers on 2D van der Waals materials and discussed various methods to perform controlled growth of semiconductor nanostructures and microstructures on 2D layers. The 2D layers’ benefits in semiconductor technology and their role in non-destr

The vanadium dioxide (VO 2 ) microstructure arrays were integrated with In x GaN 1–x light-emitting diodes (LEDs) to develop a long-wavelength infrared sensor array. By utilizing GaN-based LEDs as a readout unit, the VO 2 /LED heterostructure directly converts temperature-induced resistance changes into visible light emission. The VO 2 layer exhibits uniform chemical configuration and atomic bonding, leading to consistent metal-to-insulator transition behavior across all pixels. The low-voltage

A multi-color LED chip with integrated parabolic lenses is shown. The emission collimates within a 0.5NA zone with percentages of 75% for red, 83% for green, and 95% for blue, of the total emission, respectively.