Browsing by Author "Chuang, Chia-Wei"

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A Miniature 92-95 GHz On-chip Slow-wave Branch-line Coupler
(2018-01-01)
Chen, Yi-Tang
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Chiu, Chia-Sung
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Chuang, Chia-Wei
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Chen, Kun-Ming
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Huang, Guo-Wei
A miniature 92-95 GHz on-chip branch-line coupler (BLC) employing a slow-wave microstrip line is proposed herein. The ground metal plane beneath the signal line is periodically slotted, and the coupler can be highly miniaturized owing to the short wavelength characteristic of the transmission line with slow-wave structure. The size of the slow-wave BLC is 250 mu m X 250 mu m, which is 39% of the size of conventional BLCs.
Development and characterization of the thermal behavior of packaged cascode GaN HEMTs
(2016-01-01)
Chou, Hsin-Ping
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Cheng, Stone
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Cheng, Chia-Hsiang
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Chuang, Chia-Wei
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機械工程學系
This study investigates the heat generation behavior of packaged normally-on multi-finger AlGaN/GaN high electron mobility transistors (HEMTs) that are cascoded with a low-voltage MOSFET (LVMOS) and a SiC Schottky barrier diode (SBD). By foremost carrying out electro-thermal simulation and related thermal measurements with infrared thermography and Raman spectroscopy for basic 5 mm GaN HEMTs, the location of hot spot in operating device can be obtained. Based on the outcome, further packaged cascode GaN HEMT is analyzed. A hybrid integration of the GaN-HEMT, LVMOS, and SiC SBD are assembled on a directly bonded copper (DBC) substrate in the four-pin metal case TO-257 package. The metal plate is used as both the source terminal and heat sink. The analytical results of thermal investigation are confirmed by comparing them with the infrared thermographic measurements and numerical results obtained from a simulation using Ansys Icepak. For a power dissipation of less than 11.8 W, the peak temperature of the GaN HEMTs is 118.7 degrees C, obtained from thermal measurements. (C) 2015 Elsevier Ltd. All rights reserved.
Study of Charge Trapping Effects on AlGaN/GaN HEMTs Under UV Illumination With Pulsed I-V Measurement
(2020-06-01)
Nagarajan, Venkatesan
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Chen, Kun-Ming
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Chen, Bo-Yuan
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Huang, Guo-Wei
;
Chuang, Chia-Wei
The charge trapping effects on AlGaN/GaN HEMTs under UV illumination are investigated using the pulsed current-voltage (I-V) measurement method. The test samples are unpassivated Schottky-gate HEMTs and metal-insulator-semiconductor HEMTs (MIS-HEMTs) with SiN gate dielectric. For HEMTs, the dominant charge trapping sources are the surface trap states, whereas, for MIS-HEMTs, they are trap states in the SiN gate dielectric and GaN buffer. When these devices are shined with the UV light, the drain current increases apparently in both samples owing to the generated photocurrent. By combining the UV illumination and pulsed I-V measurement, we find out the UV light has less effect on the surface charge trapping in the unpassivated HEMTs. Moreover, in MIS-HEMTs, we observe the charge trapping in the SiN gate dielectric becomes more serious under UV illumination, whereas the charge trapping in the GaN buffer is suppressed significantly. These findings are important for designing a GaN-based HEMT for photonic applications. In addition, the different responses of the surface-, buffer-, and gate-dielectric-related charge trapping to the UV light suggest that it would be easier to distinguish the trap types by introducing the UV illumination during the pulse measurement.