Browsing by Author "Chen, Szu-Hao"

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Apparatus, system and method for stream-based data filtering
(2008-01-03)
Lin, Po-Ching
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Lin, Ying-Dar
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Chen, Szu-Hao
;
Lai, Yuan-Cheng
An apparatus, a system and a method for stream-based data filtering are disclosed. The apparatus is for filtering data transmitted from a sending end. The data is transmitted one by one by using a plurality of data segments. The data filtering apparatus includes a receiving module, a processing module and a transmission module. The receiving module is for receiving the data segments transmitted from the sending end. The processing module implements virus scanning for the data segments one by one. The transmission module then transmits the data segments which have passed through the virus scanning to a receiving end.
Bias- and Temperature-Assisted Trapping/De-trapping of R-ON Degradation in D-mode AlGaN/GaN MIS-HEMTs on a Si substrate
(2017-01-01)
Zhang, Jin-Ming
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Hsieh, Ting-En
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Wu, Tian-Li
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Chen, Szu-Hao
;
Chen, Shi-Xuan
In this study, we investigate the R-ON degradation in D-mode AlGaN/GaN MIS-HEMTs on a Si substrate via an accelerated step stress at different temperatures. We have observed a three-phase R-ON degradation behavior, which is highly correlated with a drain bias and back gate bias. First, the R-ON degradation increases till a peak value when the drain bias increases. Second, when the drain bias increases further, the R-ON degradation is reduced. Third, the R-ON degradation slowly increases again. R-ON degradation is characterized with different temperatures, the results show that 1) high temperature leads to a smaller R-ON degradation compared to the result at room temperature and 2) high temperature shifts the peak of the R-ON degradation at a lower drain bias. A possible mechanism that the trapping and de-trapping could occur due to the high temperature and high drain bias is proposed to explain the observed results.
Channel temperature measurement in hermetic packaged GaN HEMTs power switch using fast static and transient thermal methods
(2017-08-01)
Chen, Szu-Hao
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Chou, Po-Chien
;
Cheng, Stone
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機械工程學系
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Department of Mechanical Engineering
A GaN-based power device is a superior component for high-frequency and high-efficiency applications and especially for applications that involve megahertz power conversion. In this work, a fast process of static thermal resistance (R (th)) and transient thermal impedance (Z (th)) measurements are made and analyzed to determine the thermal characteristics of the channel temperature of a hermetically packaged GaN power device. Five temperature-sensitive parameters (TSPs) are measured at temperatures from 20 to 160 A degrees C. Measurements and statistical analyses included variations with temperature of on-resistance (R (on)), saturation drain current (I (Dsat)), drain conductance (g (d)), threshold voltage (V (th)), and knee voltage (V (knee)). The statistical analyses revealed the relationships between the heating curve parameter (R (on)) and the cooling curve parameters (V (knee), I (Dsat), g (d), and V (th)). The average thermal resistance values are extracted as follows: Maximum R (th) is 2.99 A degrees C W-1, minimum R (th) is 2.92 A degrees C W-1, and the variation among the five TSPs is < 3%. Conventional optical-based techniques such as infrared (IR) and micro-Raman thermography are destructive to packaged devices. Therefore, this study developed the two reliable and fast non-destructive methods for estimating channel temperature with the following features: (1) They elucidate static and transient characteristics; (2) they involve heating and cooling; and (3) they evaluate transient thermal impedance (TTI) and safe operating area (SOA). The heating curve method has advantages over cooling curve method in terms of capturing time (40 vs. 400 s, respectively), and a lower power excitation is required to obtain the transient channel temperature response.
Evaluation and Reliability Assessment of GaN-on-Si MIS-HEMT for Power Switching Applications
(2017-02-01)
Chou, Po-Chien
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Chen, Szu-Hao
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Hsieh, Ting-En
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Cheng, Stone
;
del Alamo, Jesus A.
This paper reports an extensive analysis of the physical mechanisms responsible for the failure of GaN-based metal-insulator-semiconductor (MIS) high electron mobility transistors (HEMTs). When stressed under high applied electric fields, the traps at the dielectric/III-N barrier interface and inside the III-N barrier cause an increase in dynamic on-resistance and a shift of threshold voltage, which might affect the long term stability of these devices. More detailed investigations are needed to identify epitaxy- or process-related degradation mechanisms and to understand their impact on electrical properties. The present paper proposes a suitable methodology to characterize the degradation and failure mechanisms of GaN MIS-HEMTs subjected to stress under various off-state conditions. There are three major stress conditions that include: V-DS = 0 V, off, and off (cascode-connection) states. Changes of direct current (DC) figures of merit in voltage step-stress experiments are measured, statistics are studied, and correlations are investigated. Hot electron stress produces permanent change which can be attributed to charge trapping phenomena and the generation of deep levels or interface states. The simultaneous generation of interface (and/or bulk) and buffer traps can account for the observed degradation modes and mechanisms. These findings provide several critical characteristics to evaluate the electrical reliability of GaN MIS-HEMTs which are borne out by step-stress experiments.
Evaluation of thermal performance of all-GaN power module in parallel operation
(2014-09-05)
Chou, Po-Chien
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Cheng, Stone
;
Chen, Szu-Hao
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交大名義發表
;
機械工程學系
This work presents an extensive thermal characterization of a single discrete GaN high-electron-mobility transistor (HEMT) device when operated in parallel at temperatures of 25 degrees C-175 degrees C. The maximum drain current (I-D (max)), on-resistance (R-ON), pinch-off voltage (V-p) and peak transconductance (g(m)) at various chamber temperatures are measured and correlations among these parameters studied. Understanding the dependence of key transistor parameters on temperature is crucial to inhibiting the generation of hot spots and the equalization of currents in the parallel operation of HEMTs. A detailed analysis of the current imbalance between two parallel HEMT cells and its consequential effect on the junction temperature are also presented. The results from variations in the characteristics of the parallel-connected devices further verify that the thermal stability and switching behavior of these cells are balanced. Two parallel HEMT cells are operated at a safe working distance from thermal runaway to prevent destruction of the hottest cell. (C) 2014 Elsevier Ltd. All rights reserved.
Evaluation of thermal performance of packaged GaN HEMT cascode power switch by transient thermal testing
(2016-04-05)
Chen, Szu-Hao
;
Chou, Po-Chien
;
Cheng, Stone
;
機械工程學系
;
Department of Mechanical Engineering
In this investigation, thermal transient measurements and analyses are used to study the thermal performance of a cascoded GaN power device. The method is based on the thermal characterization of the on-resistance (R-on) of the device and the synchronized current-voltage characteristics under continuous operation. The changes in R-on with temperature (25 degrees C-180 degrees C) are measured, statistically studied, and correlations investigated. The proposed method for estimating transient thermal impedance has the following characteristics: (1) it is robust and reproducible; (2) it yields a heating curve to prevent overheating for the device under test (DUT); (3) it provides in-situ current-voltage characterization; (4) it includes a transient offset correction for initial transient electrical disturbances (such as current collapse); (5) it optimizes a compact thermal model; (6) it is sensitive to package structure and design variables. This monitoring of thermal impedance variation provides a simple and fast non-destructive method for analyzing power switching devices during thermal testing. Satisfactory experimental results confirm the feasibility of in-situ current-voltage characterization and the real power varies with the thermal impedance. (C) 2015 Elsevier Ltd. All rights reserved.