Browsing by Author "Hu, Hsin-Hui"

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Analysis of temperature effects on high-frequency characteristics of RF lateral-diffused metal-oxide-semiconductor transistors
(2008-04-01)
Hu, Hsin-Hui
;
Chen, Kun-Ming
;
Huang, Guo-Wei
;
Chien, Alex
;
Cheng, Eric
In this work, the effects of temperature on the DC and RF characteristics of lateral-diffused metal-oxide-semi conductor (LDMOS) transistors were studied. Devices with different layout structures were fabricated using a 40 V LDMOS process. The temperature coefficients of the threshold voltage and channel mobility are negative and their values are similar for devices with fishbone and ring structures. In addition, we found that both the cutoff frequency (f(T)) and the maximum oscillation frequency (f(max)) decrease with increasing temperature. The variations of f(T) with different temperatures are not only affected by the change in transconductance but also affected by the drain resistance. Finally, the temperature behaviors of S-parameters were measured, and the ring structure showed less S(22) variation with different temperatures than the fishbone structure. We extracted the model parameters of the devices to explain this observation.
Characterization of RF lateral-diffused metal-oxide-semiconductor field-effect transistors with different layout structures
(2007-04-01)
Hu, Hsin-Hui
;
Chen, Kun-Ming
;
Huang, Guo-Wei
;
Chang, Chun-Yen
;
Lu, Yii-Chian
The DC and RF characteristics of lateral-diffused metal-oxide-semi conductor (LDMOS) transistors with different layout structures were studied. The devices were fabricated using a 0.5 mu m LDMOS process. The ring and fishbone structures, which are used widely in power devices, were designed and analyzed. We found that the. transconductance, on-resistance, cutoff frequency and maximum oscillation frequency were improved using the ring structure, due to a larger equivalent W/L and lower drain parasitic resistance. In addition, the self-heating effect of LDMOS transistors was also investigated by measuring the pulsed current-voltage (I-V) and pulsed RF characteristics. From the measured results, the ring structure appeared to be a better layout design for RF LDMOS transistors.
Low-Frequency Noise Characterization of AlGaN & x002F;GaN HEMTs and MIS-HEMTs Under UV Illumination
(2020-01-01)
Nagarajan, Venkatesan
;
Chen, Kun-Ming
;
Lin, Hsin-Yi
;
Hu, Hsin-Hui
;
Huang, Guo-Wei
The low-frequency noise characteristics of AlGaN & x002F;GaN HEMTs and MIS-HEMTs are investigated in the dark condition and under UV illumination. The test devices with a 3-& x03BC;m-thick GaN buffer and a 25-nm-thick Al_0.22Ga_0.78N barrier layer were fabricated on the silicon wafer. For MIS-HEMTs, a 25-nm-thick SiN layer was deposited as a gate dielectric. The measured low-frequency noises show a 1 & x002F;f spectrum and can be described by the carrier number fluctuation model. Different noise responses to the UV light between HEMTs and MIS-HEMTs were observed. By comparing the noise data in dark and under UV illumination, the noise sources under the gate and in the ungated gate-drain access region have been identified. From these results, we can find a design guideline to improve the noise and reliability of GaN-based devices for optoelectronic applications.
Temperature-dependent capacitance characteristics of RF LDMOS transistors with different layout structures
(2008-07-01)
Hu, Hsin-Hui
;
Chen, Kun-Ming
;
Huang, Guo-Wei
;
Chen, Ming-Yi
;
Cheng, Eric
In this letter, the capacitance characteristics of RF LDMOS transistors with different temperatures and layout structures were studied. In a conventional fishbone structure, the peaks in capacitances decrease with increasing temperature. For the ring structure, two peaks in a capacitance-voltage curve have been observed at high drain voltages due to the additional corner effect. in addition, peaks in gate-to-source/body capacitance decrease and peaks in gate-to-drain capacitance increase with increasing temperature at high drain voltages. By analyzing the effects of temperature on threshold voltage, quasi-saturation current, and drift depletion capacitance, the variations of capacitances with temperature were investigated.