A kinetic Monte Carlo simulation is performed in order to study the effect of Sb as a surfactant on the growth of Ge/Si(111).In our model the exchange mechanism between Ge and Sb atoms and the re-exchange mechanism in...A kinetic Monte Carlo simulation is performed in order to study the effect of Sb as a surfactant on the growth of Ge/Si(111).In our model the exchange mechanism between Ge and Sb atoms and the re-exchange mechanism in which the exchanged Ge adatom re-exchange with the lifted Sb atom to return to the surfactant layer,are considered. Our simulation shows the re-exchange process plays an important role on the growth mode transition in Ge/Sb/Si(111) system.The influences of the substrate temperature and the deposition rate on the growth of Ge/Sb/Si(111) system is discussed.展开更多
The atomic and electronic structures of T1 and In on Si（111） surfaces are investigated using the firstprinciples total energy calculations. Total energy optimizations show that the energetically favored structure is...The atomic and electronic structures of T1 and In on Si（111） surfaces are investigated using the firstprinciples total energy calculations. Total energy optimizations show that the energetically favored structure is 1/3 ML T1 adsorbed at the T4 sites on Si（111） surfaces. The adsorption energy difference of one T1 adatom between （√3 × √3） and （1 × 1） is less than that of each In adatom. The DOS indicates that TI 6p and Si 3p electrons play a very important role in the formation of the surface states. It is concluded that the bonding of TI adatoms on Si（111） surfaces is mainly polar covalent, which is weaker than that of In on Si（111）. So T1 atom is more easy to be migrated than In atom in the same external electric field and the structures of T1 on Si（111） is prone to switch between （√3 × √3） and （1 × 1）.展开更多
The directional, averaged, and density-of-states effective masses of holes have been calculated for strained Si/(111)Si1-xGex. The results for the directional effective mass show that the effect of strain makes the co...The directional, averaged, and density-of-states effective masses of holes have been calculated for strained Si/(111)Si1-xGex. The results for the directional effective mass show that the effect of strain makes the constant energy surface of "heavy" holes more obvious warping than that in relaxed Si. The [111] and [110] directional effective masses of "heavy" holes decrease significantly under strain. It is found that the averaged effective mass of "heavy" holes decreases with increasing Ge fraction, while that of "light" holes increases. The traditional concepts of heavy and light holes become insignificant when Ge fraction is close to 0.4. The strain effect monotonically reduces the density-of-states effective mass at 218, 300 and 393 K, respectively.展开更多
We report on the preparation and superconductivity of metastable γ-Ga islands on Si(111) substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation of Ga nanoislands ...We report on the preparation and superconductivity of metastable γ-Ga islands on Si(111) substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation of Ga nanoislands at various sizes with the identical γ-phase. In-situ low temperature scanning tunneling spectra reveal quantized electronic states in ultrathin Ga islands. It is found that both the lateral size and thickness of the Ga islands strongly suppress the superconductivity. Due to substantial surface energy contribution, the transition temperature Tc scales inversely with the island thickness and the minimum thickness for the occurrence of superconductivity is calculated to be two monolayers.展开更多
基金Supported by the Zhejiang Provincial Natural Science Foundation under Grant No.Y6100384
文摘A kinetic Monte Carlo simulation is performed in order to study the effect of Sb as a surfactant on the growth of Ge/Si(111).In our model the exchange mechanism between Ge and Sb atoms and the re-exchange mechanism in which the exchanged Ge adatom re-exchange with the lifted Sb atom to return to the surfactant layer,are considered. Our simulation shows the re-exchange process plays an important role on the growth mode transition in Ge/Sb/Si(111) system.The influences of the substrate temperature and the deposition rate on the growth of Ge/Sb/Si(111) system is discussed.
基金Supported by National Natural Science Foundation of China under Grant No.60476047Program for Science & Technology Innovation Talents in Universities of Henan Province under Grant No.2008HASTIT030
文摘The atomic and electronic structures of T1 and In on Si（111） surfaces are investigated using the firstprinciples total energy calculations. Total energy optimizations show that the energetically favored structure is 1/3 ML T1 adsorbed at the T4 sites on Si（111） surfaces. The adsorption energy difference of one T1 adatom between （√3 × √3） and （1 × 1） is less than that of each In adatom. The DOS indicates that TI 6p and Si 3p electrons play a very important role in the formation of the surface states. It is concluded that the bonding of TI adatoms on Si（111） surfaces is mainly polar covalent, which is weaker than that of In on Si（111）. So T1 atom is more easy to be migrated than In atom in the same external electric field and the structures of T1 on Si（111） is prone to switch between （√3 × √3） and （1 × 1）.
基金supported by the National Ministries and Commissions (Grant Nos. 51308040203 and 6139801)the Fundamental Research Funds for the Central Universities (Grant Nos. 72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2010JQ8008)
文摘The directional, averaged, and density-of-states effective masses of holes have been calculated for strained Si/(111)Si1-xGex. The results for the directional effective mass show that the effect of strain makes the constant energy surface of "heavy" holes more obvious warping than that in relaxed Si. The [111] and [110] directional effective masses of "heavy" holes decrease significantly under strain. It is found that the averaged effective mass of "heavy" holes decreases with increasing Ge fraction, while that of "light" holes increases. The traditional concepts of heavy and light holes become insignificant when Ge fraction is close to 0.4. The strain effect monotonically reduces the density-of-states effective mass at 218, 300 and 393 K, respectively.
基金supported by the National Natural Science Foundation of China(Grant No.11374336)
文摘We report on the preparation and superconductivity of metastable γ-Ga islands on Si(111) substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation of Ga nanoislands at various sizes with the identical γ-phase. In-situ low temperature scanning tunneling spectra reveal quantized electronic states in ultrathin Ga islands. It is found that both the lateral size and thickness of the Ga islands strongly suppress the superconductivity. Due to substantial surface energy contribution, the transition temperature Tc scales inversely with the island thickness and the minimum thickness for the occurrence of superconductivity is calculated to be two monolayers.
