Electrical Measurements of an AlGaN/GaN High-electron-mobility Transistor Structure Grown on Si

Zhi-Yao Zhang,Shun-Tsung Lo,Li-Hung Lin,Kuang Yao Chen,J. Z. Huang,Zhi-Hao Sun,C.-T. Liang,N. C. Chen,Chin-An Chang,P. H. Chang 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.9

We report on magnetotransport results for an Al_0.15Ga_0.85N/GaN high-electron-mobility-transistor structure grown on a p-type Si (111) substrate. Our results show that there exists an approximately temperature (<i>T</i>)-independent point, which could be ascribed to a direct transition from a weak insulator to a high Landau level filling factor quantum Hall state, exists in the longitudinal resistivity ρ_xx. The Hall resistivity decreases with increasing <i>T</i>, compelling experimental evidence for electron-electron interaction effects in a weakly-disordered two-dimensional (2D) system. We find that electron-electron interaction effects can be estimated and eliminated, giving rise to a corrected nominally temperature-independent Hall slope. By fitting the low-field magnetotransport data to conventional 2D weak localization theory, we find that the dephasing rate 1/τ_φ is proportional to <i>T</i>. Moreover, 1/τ_φ is finite as <i>T</i> → 0, evidence for zero-temperature dephasing in our system.

How Can South Asia and Sub-Saharan Africa Gain From the Next WTO Round?

( Kym Anderson ),( Shun Li Yao ) 세종대학교 경제통합연구소 (구 세종대학교 국제경제연구소) 2003 Journal of Economic Integration Vol.18 No.3

If South Asia and Sub-Saharan Africa are to become constructively engaged in the next attempt by World Trade Organization (WTO) members to liberalize trade multilaterally, they need to be convinced that there will be sufficient gains from trade reform to warrant the inevitable costs of negotiation and adjustment. This paper provides new estimates of the likely economic effects on their economies of further liberalizing world trade post-Uruguay Round. The results show that the developing countries of South Asia and Sub-Saharan Africa have much to gain from taking part in the next round. However, those gains will be far greater the more those countries are willing to embrace reform at home so as to enable their firms to take greatest advantage of the opportunities provided by the opening up of markets abroad.

A snapback‑free reverse‑conducting IGBT with multiple extraction channels

Weizhong Chen,Xuwei Lin,Shun Li,Yao Huang,Yi Huang,Zhengsheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.2

A novel Reverse-Conducting Insulated Gate Bipolar Transistor (RC-IGBT) with Multiple Extraction Channels (MEC) is proposed and investigated. The MEC is characterized by two transistors NPN1 (Nbuffer/Pbarrier/Ncollector), NPN2 (Nbuffer/Pfloat/Npoly) and short Rgap in the collector. The P-Collector, N-Collector, polysilicon and Rgap are shorted together, thus the NPN1, NPN2 and Rgap are parallel with the PNP transistor (Pbody/Nbuffer/Pcollector). At the forward conduction, the unipolar mode is effectively suppressed by the electron barriers P-barrier (the base of the NPN1) and P-float (the base of the NPN2), thus the snapback effect can be completely eliminated. At the turn-off, the electrons are quickly extracted by three channels of the NPN1, NPN2 and Rgap, thus the Eoff can be remarkably decreased. Results show at the same Von of 2.8 V, the Eoff of the MEC RC-IGBT is reduced by 20%, 37%, 45% and 59% compared to AB, FPL, DFS and TOC RC-IGBT, respectively. Therefore the excellent trade-off characteristics with snapback free are achieved.

중국의 지방정부 융자플랫폼과 지방재정 문제

최의현 ( Eui Hyun Choi ),요순 ( Shun Yao ),이지 ( Zhi Li ) 현대중국학회 2013 現代中國硏究 Vol.14 No.2

2008년 금융위기 이후 중국정부는 성장전략을 수출주도형에서 내수주도형으로 전환하였다. 내수경제의 부양을 위해 중앙정부는 덜 발전된 내륙지역을 발전시켜야 했고, 이 과정에서 지방정부의 역할이 중요해 졌다. 하지만, 경기부양 정책을 사용하기에는 충분한 재정여력을 갖지 못한 중국 지방정부는 융자플랫폼이란 조직을 만들어 은행 대출을 이용한 투자 확대 정책을 사용하게 된다. 융자플랫폼은 지방정부 산하의 국유기업으로 정부를 대신하여 고정자산투자를 집행하는 기관이다. 그런데 융자플랫폼의 투자에는 수익성 투자도 있지만, 정부가 응당 행해야할 사회간접자본 건설 투자도 상당부분 포함되어 있어 투자의 효율성이 떨어진다는 지적을 받고 있다. 본 연구에 따르면 2011년 기준으로 융자플랫폼의 부실대출 비율은 연간 은행 신규대출의 1.5∼4.8% 정도로 추산된다. 전체 규모가 아직 큰 편은 아니지만, 융자플랫폼이 본격적으로 설립 된지 2∼3 밖에 되지 않은 점을 고려하면 향후 지방발 금융부실화 가능성을 배재하지 않을 수 없다. 융자플랫폼의 설립 목적이 내수경기 부양에 있지만, 만일 지방에서의 투자가 효율성을 잃게 된다면 중국 경제에 심각한 부정적인 영향을 줄 수도 있다. Since global financial crisis in 2008, Chinese government has tried to change their economic development policy from export-led growth to domestic demand-driven growth. For the boosting domestic market, central government needs to push less developing inland regions. Local governments should undertake as key players to drive their economies under this macro policy. Generally Chinese local government are struggling under the budget constriction, so they set up loan platforms as sub-companies for boosting their fixed investment and economy instead of themselves. According to this research, the level of bad loan would become 1.5%∼4.8% (based on 2011) of the annual fresh loan in the banking sector. The amount of bad loan would occupy a small potion comparing to the volume of total banking loan because the loan from loan platform has occurred just 2 or 3 years ago and central government hardly allowed the local level loans until now. Therefore, if Chinese central government manages the loan of local loan platform more strictly, local government could easily avoid the default situation. China can strategically use a loan platform as a trigger to motivate their growth engine in a short term. However, Chinese government would approve the loan schemes indiscreetly when the Chinese economy do not revive as fast as they expected, the fiscal soundness of local government might be worsened.

Decrease of Oxygen Vacancy by Zn-Doped for Improving Solar-Blind Photoelectric Performance in β-Ga2O3 Thin Films

Daoyou Guo,Xinyuan Qin,Ming Lv,Haoze Shi,Yuanli Su,Guosheng Yao,Shunli Wang,Chaorong Li,Peigang Li,Weihua Tang 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.6

Highly (201) oriented Zn-doped β-Ga2O3 thin films with differentdopant concentrations were grown on (0001) sapphire substrates byradio frequency magnetron sputtering. With the increase of Zn dopantconcentration, the crystal lattice expands, the energy band gap shrinks,and the oxygen vacancy concentration decreases. Both the metalsemiconductor metal (MSM) structure photodetectors based on thepure and Zn-doped β-Ga2O3 thin films exhibit solar blind UVphotoelectric property. Compared to the pure β-Ga2O3 photodetector,the Zn-doped one exhibits a lower dark current, a higher photo/darkcurrent ratio, a faster photoresponse speed, which can be attributed tothe decreases of oxygen vacancy concentration.

Association Between Metabolic Risk Factors and Cognitive Impairment in Schizophrenia Based on Sex

Hongna Huang,Lizhao Du,Zhengping Pu,Yuan Shi,Zifan Xiao,Xi Chen,Shun Yao,Lijun Wang,Zezhi Li,Ting Xue,Donghong Cui 대한신경정신의학회 2023 PSYCHIATRY INVESTIGATION Vol.20 No.10

Objective Sex differences have been observed in many aspects of schizophrenia, including cognitive deficits. Despite extensive research into the relationship between metabolic factors and cognitive deficits in schizophrenia, few studies have explored the potential sex difference in their association. Methods We recruited 358 schizophrenia patients and 231 healthy controls. The participants underwent measurements of body mass index (BMI), waist circumference, blood pressure, triglycerides, high-density lipoprotein cholesterol, and fasting blood glucose. Metabolic risk factors included abdominal obesity, hypertension, hyperglycemia, and dyslipidemia. A collection of these metabolic risk factors has been defined as metabolic syndrome. These diagnoses were based on the criteria of the National Cholesterol Education Program’s Adult Treatment Panel III. Cognitive performance was measured using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). A descriptive analysis, difference analysis, and linear regression model were used to identify the metabolic risk factors for cognitive function in schizophrenia. Results Our findings revealed sex differences in the rate of abdominal obesity and hypertension in schizophrenic patients. Additionally, we observed sex differences in the association between metabolic risk factors and cognitive impairment in schizophrenia. Specifically, hyperglycemia was associated with the immediate memory index score of RBANS in male patients, while dyslipidemia was associated with language, attention, delayed memory index scores, and RBANS total score in female patients. Conclusion Our results suggest that sex should be considered when evaluating the impact of metabolic disorders on the cognitive function of schizophrenic patients. Moreover, our study identifies hyperglycemia and dyslipidemia as potential targets for precise treatment by sex stratification, which could benefit the improvement of cognitive impairment in schizophrenic patients.