Tienmo Shih

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Three-hump InGaN-based white light-emitting diodes (LEDs) precoated with traditional yellow/green phosphors and red-emitting quantum dots (QDs), have been numerically investigated. Under variations of eight correlated color temperatures (CCTs), three wavelengths, two bandwidths, and two peak heights, optimal results of luminous efficacy radiation (LER) and(More)
We propose an experimental method that determines junction temperatures in light-emitting diodes by measuring currents while holding the low forward voltages constant. In this procedure, we first calibrate current-temperature-rela- tionship parameters under the condition of negligible thermal generation. With one of the two parametric values, we discover(More)
Pulse implementation or switching-off (PISO) of electrical currents has become a common operation in junction-temperature (Tj) measurements for semiconductor devices since 2004. Here we have experimentally discovered a substantial discrepancy between Tj values with, and without, PISO (e.g., 36.8 °C versus 76.5 °C above the ambient temperature at 25.0 °C).(More)
Other than the well-known sulfurization of molybdate compound to synthesize molybdenum disulfide (MoS2 ) layers, the dynamic process in the whole crystalline growth from nuclei to triangular domains has been rarely experimentally explored. Here, a competing sulfur-capture principle jointly with strict epitaxial mechanism is first proposed for the initial(More)
The tradeoff between the color rendering index (CRI) and the luminous efficacy (LE) for candle-like three-hump white light-emitting diodes (LEDs), which consist of blue InGaN chip, yellow aluminate phosphors, and red AlGaInP chip, has been investigated. Spectral models have been separately developed for the optimization process after experimentally(More)
In this paper, we have proposed a transmission-type testing system for determining optical characteristics of remote-phosphor plates in white light-emitting diodes (WLEDs). A comparative analysis between the proposed system and a traditional reflection-type system has also been conducted. Results show that the measured optical efficiency of phosphors(More)
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