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Direct integration of InGaN/sapphire LED with a cup-shaped copper heat spreader was proposed for enhancing light extraction and heat dissipation by self-aligned photolithography and copper electroforming techniques. Based on optical simulation results, geometric design for a copper heat spreader is crucial to luminous property of an LED chip. An InGaN/sapphire LED embedded with the optimized cup-shaped copper heat spreader was demonstrated to exhibit superior light output power than a conventional LED by a factor of 2.68 times at an injection current of 1 A. Moreover, the power efficiency is remarkably increased from 4.2% to 15.7% at the same driven current. The improved device performance can be attributed to both of the enhanced light extraction of the laterally emitted light from an LED chip and efficient heat dissipation by the highly reflective and excellently thermal conductive copper heat spreader. These results suggest an efficient alternative simultaneously with two functions of thermal management and light extraction for high-power InGaN/sapphire LEDs application from chip to package design.

The optical and thermal properties of blue InGaN/sapphire LEDs with a novel structure design for heat dissipation is investigated. The LED chip is designed to directly contact with a cup-shaped Cu heat spreader, and then mounted on a heat sink coated with a diamond-like film. The packaged LED chip with the novel heat dissipation design demonstrates superior light output power and reduced junction temperature as compared with the same LED chip packaged using conventional process.

Silicon nitride (SiNx) films deposited on Ar, N2, and O2 plasma-treated polycarbonate (PC) substrates have been investigated for transparent barrier applications. The details on different gas effects on PC surface and SiNx/PC properties were investigated in terms of the contact angle, free energy, roughness, adhesion, transmittance, water vapor transmission rate (WVTR) and oxygen transmission rate (OTR). It was found that both Ar and N2 plasma could improve the adhesion between SiNx films and PC substrates. When the roughness of plasma-treated PC substrates was decreased from 1.71 nm to 0.89 nm, the OTR data of SiNx/PC samples after 6000 times bending test was decreased from 0.61 to 0.1 cm3/m2/day. Moreover, the transmittance and permeation results of SiNx/PC plasma-treated samples also show great dependence. After Ar plasma treatment for 60 s, the WVTR and OTR of the 50-nm-thick SiNx barrier coating on PC substrate after 6000 times bending test can decrease to a value of near 0.01 g/m2/day and 0.1 cm3/m2/day, respectively. This result indicates that the SiNx films on Ar plasma-treated PC substrates have high potential for flexible organic light-emitting diode applications.

To improve light extraction efficiency and heat dissipation of sapphire-based light-emitting diodes (LEDs), we develop and optimize copper heat spreader which was electroformed in close contact with sapphire. On the basis of simulation results, an LED with copper lowers junction temperature when compared with the LED without copper. In addition, a copper-surrounded LED with protruded bottom surface exhibits almost the same thermal performance as that with flat bottom surface. In practical fabrication, all the LED samples with copper show significant reduction in junction temperature form 150.4°C for the original LED to less than 100°C at injection current of 1 A (∼ 3 W/mm2). The encapsulated LED at the same driven current yields an output power of ∼700 mW, which is 2.7 times higher than that of the original LED without copper.

To transform endless energy from ambient vibration into useful power. We scavenge mechanical energy and transfer into electrical energy by utilizing piezoelectric materials. We compare generators performance at different situations and then let electric energy be charged to a Ni-MH battery or a capacitor through a full wave rectifier. We also obtain resonance of piezoelectric benders by system identification which can be an important reference when designing the generator. This study proposes a novel mechanism comprising a mass-spring system and magnet repulsive force. According to finite element software and experimental result, below 5 Hz the generator absorbs vibration energy more easily. We have investigated the influence of the mass magnitude and obtained the optimum result of 2.7 V and 0.379 muw when the swinging amplitude of the motor is plusmn1.8 deg at swinging frequency of 3.96 Hz.