S. J. Chang

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Phase change materials (PCMs) have been used in various fields including the materials of buildings. In this research, mixed shape-stabilized PCMs (Mixed SSPCMs) were prepared by impregnating coconut oil and n-hexadecane into exfoliated graphite nanoplatelets (xGnP) through a vacuum impregnate method. Coconut oil is fatty acid ester PCM which is relatively(More)
Nitride-based light emitting diodes (LEDs) with internal electrostatic discharge (ESD) protection diodes emitting at 460 nm were proposed and realized. By building an internal GaN p-n junction diode, negative ESD induced pulse current could flow through the protection diode without damaging the major LED. It was found that operation voltage and ESD(More)
Changes in electrical as well as surface composition such as chemical and electronic properties of Mg-doped p-type GaN by phosphorus implanting are systematically investigated using Hall effect and X-ray photoelectron spectroscopy (XPS) measurements. It is shown that p-type conductivity of Mg-doped GaN can be improved by implanting P atoms after a proper(More)
A fully matched Ka-band wideband pseudomorphic high-electron-mobility transistor (PHEMT) 1-W monolithic millimeter-wave integrated circuit (MMIC) high-power amplifier (HPA) without any external circuit is developed. The two-stage HPAs are prepared on 2-mil GaAs substrates with a small chip size of 3.46 ϫ 2.9 mm. At least 10-dB small-signal gain, 29.5 dBm P(More)