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Your search keyword '"Chang, Kai-Chun"' showing total 8 results
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8 results on '"Chang, Kai-Chun"'

5. Phase transformation on HZO ferroelectric layer in ferroelectric random-access memory induced by x-ray irradiation.

Author

Wu, Chung-Wei, Chen, Po-Hsun, Chang, Ting-Chang, Tan, Yung-Fang, Lin, Shih-Kai, Yeh, Yu-Hsuan, Zhang, Yong-Ci, Lin, Hsin-Ni, Chang, Kai-Chun, Yeh, Chien-Hung, and Sze, Simon

Subjects
PHASE transitions, X-rays, CURRENT-voltage curves, RF values (Chromatography), STRAY currents, IRRADIATION
Abstract

In this study, electrical measurements on ferroelectric random-access memory by prior x-ray irradiation are conducted. Compared with an unirradiated device, parameters such as current leakage and remnant polarization of the irradiated device were unexpectedly improved. Besides, better reliabilities including the number of endurance times and retention time have also been demonstrated. To clarify the underlying physical mechanism, the electrical properties are analyzed. The current–voltage curve (I–V) implies a change in the grain size in the ferroelectric layer (FL), and the capacitance–voltage curve (C – V) profile indicates that the FL undergoes a phase change during irradiation. Finally, according to the electrical results, a physical model is proposed as an explanation. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Analysis of Abnormal C–V Hump on Si3N4 MIS-HEMT With Mesa Isolation Under Negative Gate Bias Stress

Author

Lee, Ya-Huan, Chang, Kai-Chun, Lin, Hsin-Ni, Tai, Mao-Chou, Huang, Wei-Chen, Lin, Jia-Hong, Kuo, Hung-Ming, Lee, Jason, Huang, I-Yu, and Chang, Ting-Chang

Abstract

In this study, negative gate bias stress (NGBS) is applied to the Si3N4 metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs). The gate electron injected into the Si3N4 dielectric layer and the holes generated by the impact ionization trapped into the AlGaN layer are the two main degradation mechanisms, which cause the unstable threshold voltage. Moreover, it is discovered that an abnormal ${C}$ – ${V}$ hump is generated after NGBS because of the uneven hole trapping at the AlGaN near the channel under the gate. The unusual direction of the electric field, which is related to the mesa isolation technology, is observed under NGBS condition in the Silvaco TCAD simulation. The location of the hole trapping is verified by the positive gate bias after NGBS during the recovery time. Finally, the device without the mesa isolation is used to verify the abnormal degradation results.

Published
2024
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7. The Transition of Threshold Voltage Shift of Al2O3/Si3N4 AlGaN/GaN MIS-HEMTs Under Negative Gate Bias Stress From DC to AC

Author

Lee, Ya-Huan, Chang, Kai-Chun, Tai, Mao-Chou, Wang, Yu-Xuan, Lin, Hsin-Ni, Yeh, Yu-Hsuan, Kuo, Hung-Ming, Tsai, Xin-Ying, Lee, Jason, Huang, I-Yu, Chang, Ting-Chang, and Sze, Simon

Abstract

In this study, the reliability issues are discussed under dc and ac negative gate bias stress (ac-NGBS) in Al2O3/Si3N4 metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs). Converse degradation between these two stress conditions is discovered. The holes generated by trap-assisted thermionic field emission (TA-TFE) are trapped into the Al2O3 layer, so that the threshold voltage ( ${V}_{\text {th}}$ ) decreases under dc negative gate bias stress (dc-NGBS). ${V}_{\text {th}}$ increases because of the hot electrons injected into the GaN layer, while the device is turned on quickly under ac-NGBS. In addition, the degradation mechanisms under dc-NGBS and ac-NGBS are confirmed by the OFF-state gate and drain leakages, respectively. Silvaco TCAD is used to validate the degradation mechanism under ac-NGBS. Finally, the characteristics of the ${V}_{\text {th}}$ shift transition from dc to ac NGBS are discussed.

Published
2024
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8. Effect of body mass index on mortality for diabetic patients with aortic stenosis.

Author

Chang KC, Ho LT, Huang KC, Hsu JC, Kuan DT, Lin TT, Lee JK, Yang YY, Chuang SL, and Lin LY

Subjects
Humans, Male, Female, Aged, Middle Aged, Aged, 80 and over, Risk Factors, Echocardiography, Thinness complications, Thinness mortality, Body Mass Index, Diabetes Mellitus, Type 2 complications, Diabetes Mellitus, Type 2 mortality, Aortic Valve Stenosis mortality, Aortic Valve Stenosis complications, Obesity complications, Obesity mortality
Abstract

Background: Several studies suggest an "obesity paradox," associating obesity with better cardiovascular outcomes in patients with type 2 diabetes mellitus (DM) or aortic stenosis (AS) compared to normal or underweight individuals. This study explores the impact of body mass index (BMI) on diabetic patients with AS., Methods: Between 2014 and 2019, patients with DM who underwent echocardiography were analyzed. Outcomes included all-cause mortality, cardiovascular, and non-cardiovascular death. Patients were categorized as underweight, normal weight, or obese based on BMI (<18.5, 18.5 to 27, and >27 kg/m2, respectively)., Results: Among 74,835 DM patients, 734 had AS. Normal weight comprised 65.5% (n=481), underweight 4.1% (N=30), and 30.4% were obese. Over a 6-year follow-up, underweight patients had significantly higher all-cause mortality (HR 1.96, 95% CI 1.22 - 3.14, p = 0.005), while obese patients had significantly lower mortality (HR 0.79, 95% CI 0.68 - 0.91, p=0.001) compared to the normal group. Regarding etiologies, underweight patients had a higher risk of non-cardiovascular death (HR 2.47, 95% CI 1.44-4.25, p = 0.001), while obese patients had a lower risk of cardiovascular death (HR 0.66, 95% CI 0.50-0.86, p=0.003). Subgroup analysis showed a consistent trend without significant interaction., Conclusions: BMI significantly impacts mortality in DM patients with AS. Being underweight is associated with worse non-cardiovascular death, while obesity is linked to improved cardiovascular death outcomes.

Published
2024
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