Browsing by Author "Chi, J"

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Performance of AlGaN/GaN heterostrucrure FETs over temperatures
(2004)
Lee, CC
;
Shih, CF
;
Lee, CP
;
Tu, RC
;
Chuo, CC
In this article, a comparison on the device performance of the undoped and modulation-doped AlGaN/GaN HFETs over temperatures was presented. The results obtained indicated that the device structure has a significant influence on the device performance. The modulation-doped devices are superior to the undoped devices over the temperatures studied. The stability (the temperature dependence of device performance), however. is not as good as the undoped devices.
Quaternary AlInGaN multiple quantum well 368 nm light-emitting diode
(2006-01-25)
Wang, TC
;
Kuo, HC
;
Lee, ZH
;
Chuo, CC
;
Tsai, MY
We report high output power from AlInGaN multiple quantum well (MQW) ultraviolet light-emitting diodes. The high Al containing cladding layer, electron blocking layer and p-contact layer were chosen for transparency at 365 nm to reduce the internal absorption, reduce electron overflow and enhance output power. The UV output power was as high as 1.52 mW at 20 mA at 368 nm under room temperature CW operation. The maximum output power in CW operation is 11 mW at 170 mA. In this letter, we demonstrate a helpful and easy way to measure and calculate the junction temperature of AlInGaN UVLEDs. (c) 2005 Elsevier B.V. All rights reserved.
Temperature-dependent electron transport properties of AlGaN/GaN heterostructures
(2004-06-01)
Lee, CC
;
Shih, CF
;
Lee, CP
;
Tu, RC
;
Chuo, CC
In this article, a comparison on the temperature dependence of the electron transport properties of the undoped and modulation-doped AlGaN/GaN heterostructures is presented. The results obtained indicate that the device structure plays an important role in the temperature-dependent transport behavior of the devices. The undoped structure has a nearly constant 2DEG concentration over a wide temperature range. The modulation-doped structure has a temperature-dependent electron concentration. The increase in electron concentration in the modulation-doped structure at high temperatures is due to the thermal activation of Si donors in the AlGaN layer. In addition, the modulation-doped structure shows comparable electron mobility with the undoped structure at high temperatures, indicating that the modulation-doped structure would exhibit a better device performance at high temperatures.
Temperature-dependent optical properties of In0.34Ga0.66As1-xNx/GaAs single quantum well with high nitrogen content for 1.55 mu m application grown by molecular beam epitaxy
(2006-05-15)
Lai, FI
;
Kuo, SY
;
Wang, JS
;
Hsiao, RS
;
Kuo, HC
The temperature dependence of optical properties of InGaAsN/GaAs single-quantum wells grown by solid source molecular beam epitaxy (MBE) with N contents varied from 0% to 5.3% was investigated by photoluminescence (PL). The evolution of the peak positions of InGaAs/GaAs sample are in agreement with the empirical Varshni model. However, pronounced temperature-dependent S-shaped peak positions and N-shaped linewidth were observed in PL spectra while increasing nitrogen concentration. The activation energy of InGaAsN/GaAs single quantum well (SQWs) is observed to decrease with nitrogen incorporation, which is contrary to the expectation of the bandgap reduction. This phenomenon suggests that the existence of defect-related nonradiative processes is due to nitrogen incorporation. The results of measurement demonstrate that the nitrogen incorporation into the InGaAsN has strong influence not only on carrier localization but also on the optical quality. In addition, the growth of high nitrogen content (5.3%) shows that the InGaAsN might be the potential candidate for long-wavelength optoelectronic devices. (c) 2006 Elsevier B.V. All rights reserved.
Ultra-high-density InGaN quantum dots grown by metalorganic chemical vapor deposition
(2004-02-15)
Tu, RC
;
Tun, CJ
;
Chuo, CC
;
Lee, BC
;
Tsai, CE
This study examined how the duration of SiNx treatment on an underlying GaN layer affects the optical property, surface morphology and density of following InGaN quantum dots (QDs). InGaN QDs with extremely high density of near 3 x 10(11) cm(-2) exhibited strong photoluminescence (PL) emission at room temperature (RT). Increasing the duration of the SiN, treatment of the underlying GaN layer, the RT-PL peak of the following InGaN nano-islands and QDs was found to be red-shifted from the violet to the greenish region, and the spectrum was broadened. Additionally, the average height of InGaN nano-islands and QDs increased with the duration of SiNs treatment, explaining the redshift of the RT-PL peak.