Arsenic can diffuse into high-κ dielectrics during OaAs-based metal oxide semiconductor transistor process, which causes the degradation of gate dielectrics. To explore the origins of the degradation, we employ nonlo...Arsenic can diffuse into high-κ dielectrics during OaAs-based metal oxide semiconductor transistor process, which causes the degradation of gate dielectrics. To explore the origins of the degradation, we employ nonlocal B3LYP hybrid functional to study arsenic related defects in ZrO2. Via band alignments between the OaAs and ZrO2, we are able to determine the defect formation energy in the GaAs relative to the ZrO2 band gap and assess how they will affect the device performance. Arsenic at the interstitial site serves as a source of positive fixed charge while at the oxygen or zirconium substitutional site changes its charge state within the band gap of GaAs. Moreover, it is found that arsenic related defects produce conduction band offset reduction and gap states, which will increase the gate leakage current.展开更多
采用简单团簇模型结合密度泛函理论研究了CH3OH在Ga-rich Ga As(001)-(4×2)表面上的吸附与解离过程.计算结果表明,CH3OH在Ga-rich Ga As(001)-(4×2)表面上首先会形成两种化学吸附状态,然后CH3OH经解离生成CH3O自由基和H原子...采用简单团簇模型结合密度泛函理论研究了CH3OH在Ga-rich Ga As(001)-(4×2)表面上的吸附与解离过程.计算结果表明,CH3OH在Ga-rich Ga As(001)-(4×2)表面上首先会形成两种化学吸附状态,然后CH3OH经解离生成CH3O自由基和H原子吸附在表面不同位置上.通过比较各个吸附解离路径,发现解离后的H原子相对更容易吸附在位于表面第二层紧邻的As原子上.展开更多
The stability, infrared spectra and electronic structures of （ZrO2）n （n= 3--6） clusters have been investigated by using density-functional theory （DFT） at B3LYP/6-31 G＊ level. The lowest-energy structures have ...The stability, infrared spectra and electronic structures of （ZrO2）n （n= 3--6） clusters have been investigated by using density-functional theory （DFT） at B3LYP/6-31 G＊ level. The lowest-energy structures have been recognized by considering a number of structural isomers for each cluster size. It is found that the lowest-energy （ZrO2）5 cluster is the most stable among the （ZrO2）n （n=3--6） clusters. The vibration spectra of Zr-O stretching motion from terminal oxygen atom locate between 900 and 1000 cm 1, and the vibrational band of Zr---O--Zr--O four member ring is obtained at 600~700 cm ^-1, which are in good agreement with the experimental results. Mulliken populations and NBO charges of （ZrO2）n clusters indicate that the charge transfers occur between 4d orbital of Zr atoms and 2p orbital of O atoms. HOMO-LUMO gaps illustrate that chemical stabilities of the lowest-energy （ZrO2）,, （n = 3--6） clusters display an even-odd alternating pattern with increasing cluster size.展开更多
基金Supported by the Key Project of Education Department of China under Grant No 211035the Science Foundation from Education Department of Liaoning Province under Grant No L2014445
文摘Arsenic can diffuse into high-κ dielectrics during OaAs-based metal oxide semiconductor transistor process, which causes the degradation of gate dielectrics. To explore the origins of the degradation, we employ nonlocal B3LYP hybrid functional to study arsenic related defects in ZrO2. Via band alignments between the OaAs and ZrO2, we are able to determine the defect formation energy in the GaAs relative to the ZrO2 band gap and assess how they will affect the device performance. Arsenic at the interstitial site serves as a source of positive fixed charge while at the oxygen or zirconium substitutional site changes its charge state within the band gap of GaAs. Moreover, it is found that arsenic related defects produce conduction band offset reduction and gap states, which will increase the gate leakage current.
文摘采用简单团簇模型结合密度泛函理论研究了CH3OH在Ga-rich Ga As(001)-(4×2)表面上的吸附与解离过程.计算结果表明,CH3OH在Ga-rich Ga As(001)-(4×2)表面上首先会形成两种化学吸附状态,然后CH3OH经解离生成CH3O自由基和H原子吸附在表面不同位置上.通过比较各个吸附解离路径,发现解离后的H原子相对更容易吸附在位于表面第二层紧邻的As原子上.
基金Project supported by the National Natural Science Foundation of China （No. 20876005） and the National Basic Research Program of China （No. 2010CB732301 ）.
文摘The stability, infrared spectra and electronic structures of （ZrO2）n （n= 3--6） clusters have been investigated by using density-functional theory （DFT） at B3LYP/6-31 G＊ level. The lowest-energy structures have been recognized by considering a number of structural isomers for each cluster size. It is found that the lowest-energy （ZrO2）5 cluster is the most stable among the （ZrO2）n （n=3--6） clusters. The vibration spectra of Zr-O stretching motion from terminal oxygen atom locate between 900 and 1000 cm 1, and the vibrational band of Zr---O--Zr--O four member ring is obtained at 600~700 cm ^-1, which are in good agreement with the experimental results. Mulliken populations and NBO charges of （ZrO2）n clusters indicate that the charge transfers occur between 4d orbital of Zr atoms and 2p orbital of O atoms. HOMO-LUMO gaps illustrate that chemical stabilities of the lowest-energy （ZrO2）,, （n = 3--6） clusters display an even-odd alternating pattern with increasing cluster size.
