The H2Ge=Ge：, as well as and its derivatives （X2Ge=Ge：, X=H, Me, F, C1, Br, Ph, At, ...） is a kind of new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of t...The H2Ge=Ge：, as well as and its derivatives （X2Ge=Ge：, X=H, Me, F, C1, Br, Ph, At, ...） is a kind of new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of the cycloaddition reaction between singlet Me2Ge=Ge： and acetaldehyde was investigated with the B3LYP/6-31G＊ method in this work. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule is that the two reactants firstly form a four-membered Ge-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Ge-heterocyclic ring germylene and the ~ orbital of acetaldehyde forming a r^--~p donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with acetaldehyde to form an intermedi- ate. Because the Ge atom in intermediate happens sp3 hybridization after transition state, then, intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. The research result indicates the laws of cycloaddition reaction between Me2Ge=Ge： and ac- etaldehyde, and lays the theory foundation of the cycloaddition reaction between H2Ge=Ge： and its derivatives （X2Ge=Ge：, X=H, Me, F, C1, Br, Ph, At, ...） and asymmetric ^-bonded compounds, which are significant for the synthesis of small-ring and spiro-Ge-heterocyclic ring compounds.展开更多
H2Ge=Si： and its derivatives （X2Ge=Si：, X=H, Me, F, C1, Br, Ph, Ar, ...） are new species. Its cycloaddition reactions are new area for the study of silylene chemistry. The cycloaddition reaction mechanism of singl...H2Ge=Si： and its derivatives （X2Ge=Si：, X=H, Me, F, C1, Br, Ph, Ar, ...） are new species. Its cycloaddition reactions are new area for the study of silylene chemistry. The cycloaddition reaction mechanism of singlet H2Ge=Si： and formaldehyde has been investigated with the MP2/aug-cc-pVDZ method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule is that two reactants firstly form a four-membered Ge-heterocyclic ring silylene through the [2＋2] cycloaddition reaction. Because of the 3p unoccupied orbital of Si： atom in the four-membered Ge-heterocyclic ring silylene and the π orbital of formaldehyde forming a π--p donor-acceptor bond, the four-membered Ge-heterocyclic ring silylene further combines with formaldehyde to form an intermediate. Because the Si： atom in the intermediate undergoes sp3 hybridization after transition state, then the intermediate isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state. The result indicates the laws of cycloaddition reaction between H2Ge=Si： or its derivatives （X2Ge=Si：, X=H, Me, F, Cl, Br, Ph, Ar, ...） and asymmetric π-bonded compounds are significant for the synthesis of small-ring involving Si and Ge and spiro-Si-heterocyclic ring compounds involving Ge.展开更多
The mechanism of cycloaddition reaction between singlet state H2Ge=Ge： and acetaldehyde has been investigated with the MP2/6-311＋＋G＊＊ method. From the potential energy profile, it could be predicted that the reac...The mechanism of cycloaddition reaction between singlet state H2Ge=Ge： and acetaldehyde has been investigated with the MP2/6-311＋＋G＊＊ method. From the potential energy profile, it could be predicted that the reaction has two competitive dominant reaction pathways. The reaction rule presented is that the two reactants firstly form a four-membered Ge-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. As the 4p unoccupied orbital of Ge： atom in the four-membered Ge-heterocyclic ring germylene and the π orbital of acetaldehyde form a π→p donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with acetaldehyde to give an intermediate. Because the Ge atom in intermediate exhibits sp3 hybridization after transition state, the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. Simultaneously, the ring strain of the four-membered Ge-heterocyclic ring germylene makes it isomerize to a twisted four-membered ring product.展开更多
This work presents a unique and robust approach for validation of using the box-triangular germanium profile in the base of SiGe heterojunction bipolar transistors, where the methodology considers the simultaneous opt...This work presents a unique and robust approach for validation of using the box-triangular germanium profile in the base of SiGe heterojunction bipolar transistors, where the methodology considers the simultaneous optimization of the p-type base doping profile in conjunction with the germanium profile in the base. The study analyses the electron motion across the SiGe base in SiGe HBTs, owing to different accelerating electric fields. The analysis first presents a figure of merit, to achieve the minimum electron transit time across the base in conjunction with the increased current gain in n-p-n-SiGe HBTs, which shows a general trend vis-a-vis the advantage of a trapezoid germanium profile, but with additional accuracy as we considered simultaneously optimized p-type base doping. The effect of minority carrier velocity saturation is then included to make the study more detailed. The analysis then investigates the shifted germanium profile in the base to further minimize the base transit time. Finally, it is shown that a shifted germanium profile eventually evolves into a box-triangular Ge-profile in the SiGe base, which could simultaneously minimize the base transit time and reduce emitter delay by virtue of the high current gain. The analysis verifies that for an average Ge-dose of 7.5% Ge across the base, a box-triangular germanium profile in conjunction with an optimum base doping profile has an approximately identical base transit time and a 30% higher current gain, in comparison with an optimum base doping and triangular Ge-profile across the whole base.展开更多
X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： a...X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： and formaldehyde has been investigated with the CCSD（T）//MP2/cc-pvtz method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule presented is that the two reactants first form a four-membered Si-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Si-heterocyclic ring germylene and the π orbital of formaldehyde form a π→p donor-acceptor bond, the four-membered Si-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in the intermediate undergoes sp^3 hybridization after transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound involving Si via a transition state. The research result indicates the laws of cycloaddition reaction between HzSi=Ge： and formaldehyde. It has important reference value for the cycloaddition reaction between X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar…） and asymmetric to-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds involving Si. The study extends research area and enriches the research content of germylene chemistry.展开更多
The X2Ge=Si： （X = H, Me, F, reaction is a new area for the study of silylene between singlet CI2Ge=Si： and formaldehyde CI, Br, Ph, At...） is a new species. Its cycloaddition chemistry. The mechanism of cycloaddit...The X2Ge=Si： （X = H, Me, F, reaction is a new area for the study of silylene between singlet CI2Ge=Si： and formaldehyde CI, Br, Ph, At...） is a new species. Its cycloaddition chemistry. The mechanism of cycloaddition reaction has been investigated with CCSD（T）//MP2/6-31G＊ method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The reaction rule presented is that the two reactants firstly form a four-membered Ge-heterocyclic ring silylene through the [2＋2] cycloaddition reaction. Owing to the 3p unoccupied orbital of Si： atom in the four-membered Ge-heterocyclic ring silylene and the π orbital of formaldehyde forming a π-p donor-acceptor bond, the four-membered Ge-heterocyclic ring silylene further combines with formaldehyde to form an intermediate. Because the Si： atom in intermediate shows sp3 hybridization after transition state, the intermediate isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state. Simultaneously, the ring strain of the four-membered Ge-heterocyclic ring silylene makes it isomerize to a twisted four-membered ring product. The research result indicates the laws of cycloaddition reaction between X2Ge=Si： （X = H, Me, F, C1, Br, Ph, Ar...） and the asymmetric g-bonded compounds, which are significant for the synthesis of small-ring and spiro-Si-heterocyclic ring compound involving Ge The study extends the research area and enriches the research content of silvlene chemistrv.展开更多
文摘The H2Ge=Ge：, as well as and its derivatives （X2Ge=Ge：, X=H, Me, F, C1, Br, Ph, At, ...） is a kind of new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of the cycloaddition reaction between singlet Me2Ge=Ge： and acetaldehyde was investigated with the B3LYP/6-31G＊ method in this work. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule is that the two reactants firstly form a four-membered Ge-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Ge-heterocyclic ring germylene and the ~ orbital of acetaldehyde forming a r^--~p donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with acetaldehyde to form an intermedi- ate. Because the Ge atom in intermediate happens sp3 hybridization after transition state, then, intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. The research result indicates the laws of cycloaddition reaction between Me2Ge=Ge： and ac- etaldehyde, and lays the theory foundation of the cycloaddition reaction between H2Ge=Ge： and its derivatives （X2Ge=Ge：, X=H, Me, F, C1, Br, Ph, At, ...） and asymmetric ^-bonded compounds, which are significant for the synthesis of small-ring and spiro-Ge-heterocyclic ring compounds.
文摘H2Ge=Si： and its derivatives （X2Ge=Si：, X=H, Me, F, C1, Br, Ph, Ar, ...） are new species. Its cycloaddition reactions are new area for the study of silylene chemistry. The cycloaddition reaction mechanism of singlet H2Ge=Si： and formaldehyde has been investigated with the MP2/aug-cc-pVDZ method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule is that two reactants firstly form a four-membered Ge-heterocyclic ring silylene through the [2＋2] cycloaddition reaction. Because of the 3p unoccupied orbital of Si： atom in the four-membered Ge-heterocyclic ring silylene and the π orbital of formaldehyde forming a π--p donor-acceptor bond, the four-membered Ge-heterocyclic ring silylene further combines with formaldehyde to form an intermediate. Because the Si： atom in the intermediate undergoes sp3 hybridization after transition state, then the intermediate isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state. The result indicates the laws of cycloaddition reaction between H2Ge=Si： or its derivatives （X2Ge=Si：, X=H, Me, F, Cl, Br, Ph, Ar, ...） and asymmetric π-bonded compounds are significant for the synthesis of small-ring involving Si and Ge and spiro-Si-heterocyclic ring compounds involving Ge.
基金supported by the National Natural Science Foundation of China(No.51102114)
文摘The mechanism of cycloaddition reaction between singlet state H2Ge=Ge： and acetaldehyde has been investigated with the MP2/6-311＋＋G＊＊ method. From the potential energy profile, it could be predicted that the reaction has two competitive dominant reaction pathways. The reaction rule presented is that the two reactants firstly form a four-membered Ge-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. As the 4p unoccupied orbital of Ge： atom in the four-membered Ge-heterocyclic ring germylene and the π orbital of acetaldehyde form a π→p donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with acetaldehyde to give an intermediate. Because the Ge atom in intermediate exhibits sp3 hybridization after transition state, the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. Simultaneously, the ring strain of the four-membered Ge-heterocyclic ring germylene makes it isomerize to a twisted four-membered ring product.
文摘This work presents a unique and robust approach for validation of using the box-triangular germanium profile in the base of SiGe heterojunction bipolar transistors, where the methodology considers the simultaneous optimization of the p-type base doping profile in conjunction with the germanium profile in the base. The study analyses the electron motion across the SiGe base in SiGe HBTs, owing to different accelerating electric fields. The analysis first presents a figure of merit, to achieve the minimum electron transit time across the base in conjunction with the increased current gain in n-p-n-SiGe HBTs, which shows a general trend vis-a-vis the advantage of a trapezoid germanium profile, but with additional accuracy as we considered simultaneously optimized p-type base doping. The effect of minority carrier velocity saturation is then included to make the study more detailed. The analysis then investigates the shifted germanium profile in the base to further minimize the base transit time. Finally, it is shown that a shifted germanium profile eventually evolves into a box-triangular Ge-profile in the SiGe base, which could simultaneously minimize the base transit time and reduce emitter delay by virtue of the high current gain. The analysis verifies that for an average Ge-dose of 7.5% Ge across the base, a box-triangular germanium profile in conjunction with an optimum base doping profile has an approximately identical base transit time and a 30% higher current gain, in comparison with an optimum base doping and triangular Ge-profile across the whole base.
基金supported by the National Natural Science Foundation of China(No.51102114)
文摘X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： and formaldehyde has been investigated with the CCSD（T）//MP2/cc-pvtz method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule presented is that the two reactants first form a four-membered Si-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Si-heterocyclic ring germylene and the π orbital of formaldehyde form a π→p donor-acceptor bond, the four-membered Si-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in the intermediate undergoes sp^3 hybridization after transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound involving Si via a transition state. The research result indicates the laws of cycloaddition reaction between HzSi=Ge： and formaldehyde. It has important reference value for the cycloaddition reaction between X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar…） and asymmetric to-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds involving Si. The study extends research area and enriches the research content of germylene chemistry.
基金supported by the National Natural Science Foundation of China(No.51102114)
文摘The X2Ge=Si： （X = H, Me, F, reaction is a new area for the study of silylene between singlet CI2Ge=Si： and formaldehyde CI, Br, Ph, At...） is a new species. Its cycloaddition chemistry. The mechanism of cycloaddition reaction has been investigated with CCSD（T）//MP2/6-31G＊ method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The reaction rule presented is that the two reactants firstly form a four-membered Ge-heterocyclic ring silylene through the [2＋2] cycloaddition reaction. Owing to the 3p unoccupied orbital of Si： atom in the four-membered Ge-heterocyclic ring silylene and the π orbital of formaldehyde forming a π-p donor-acceptor bond, the four-membered Ge-heterocyclic ring silylene further combines with formaldehyde to form an intermediate. Because the Si： atom in intermediate shows sp3 hybridization after transition state, the intermediate isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state. Simultaneously, the ring strain of the four-membered Ge-heterocyclic ring silylene makes it isomerize to a twisted four-membered ring product. The research result indicates the laws of cycloaddition reaction between X2Ge=Si： （X = H, Me, F, C1, Br, Ph, Ar...） and the asymmetric g-bonded compounds, which are significant for the synthesis of small-ring and spiro-Si-heterocyclic ring compound involving Ge The study extends the research area and enriches the research content of silvlene chemistrv.
