In this paper,the dispersion relationship is derived by using the k·p method with the help of the perturbation theory,and we obtain the analytical expression in connection with the deformation potential.The calcu...In this paper,the dispersion relationship is derived by using the k·p method with the help of the perturbation theory,and we obtain the analytical expression in connection with the deformation potential.The calculation of the valence band of the biaxial strained Ge/（001）Si1-xGex is then performed.The results show that the first valence band edge moves up as Ge fraction x decreases,while the second valence band edge moves down.The band structures in the strained Ge/（001）Si 0.4 Ge 0.6 exhibit significant changes with x decreasing in the relaxed Ge along the [0,0,k] and the [k,0,0] directions.Furthermore,we employ a pseudo-potential total energy package（CASTEP） approach to calculate the band structure with the Ge fraction ranging from x = 0.6 to 1.Our analytical results of the splitting energy accord with the CASTEP-extracted results.The quantitative results obtained in this work can provide some theoretical references to the understanding of the strained Ge materials and the conduction channel design related to stress and orientation in the strained Ge pMOSFET.展开更多
This paper describes a method using both reduced pressure chemical vapor deposition （RPCVD） and ultrahigh vacuum chemical vapor deposition （UHVCVD） to grow a thin compressively strained Ge film. As the first step,...This paper describes a method using both reduced pressure chemical vapor deposition （RPCVD） and ultrahigh vacuum chemical vapor deposition （UHVCVD） to grow a thin compressively strained Ge film. As the first step, low temperature RPCVD was used to grow a fully relaxed SiGe virtual substrate layer at 500 ℃ with a thickness of 135 nm, surface roughness of 0.3 nm, and Ge content of 77%. Then, low temperature UHVCVD was used to grow a high quality strained pure Ge film on the SiGe virtual substrate at 300 ℃ with a thickness of 9 nm, surface roughness of 0.4 nm, and threading dislocation density of - 10^5 cm^-2. Finally, a very thin strained Si layer of 1.5-2 nm thickness was grown on the Ge layer at 550 ℃ for the purpose of passivation and protection. The whole epitaxial layer thickness is less than 150 nm. Due to the low growth temperature, the two-dimensional layer-by-layer growth mode dominates during the epitaxial process, which is a key factor for the growth of high quality strained Ge films.展开更多
基金Project supported by the Fundamental Research Funds for the Central Universities,China (Grant Nos. 72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province,China (Grant No. 2010JQ8008)
文摘In this paper,the dispersion relationship is derived by using the k·p method with the help of the perturbation theory,and we obtain the analytical expression in connection with the deformation potential.The calculation of the valence band of the biaxial strained Ge/（001）Si1-xGex is then performed.The results show that the first valence band edge moves up as Ge fraction x decreases,while the second valence band edge moves down.The band structures in the strained Ge/（001）Si 0.4 Ge 0.6 exhibit significant changes with x decreasing in the relaxed Ge along the [0,0,k] and the [k,0,0] directions.Furthermore,we employ a pseudo-potential total energy package（CASTEP） approach to calculate the band structure with the Ge fraction ranging from x = 0.6 to 1.Our analytical results of the splitting energy accord with the CASTEP-extracted results.The quantitative results obtained in this work can provide some theoretical references to the understanding of the strained Ge materials and the conduction channel design related to stress and orientation in the strained Ge pMOSFET.
基金Project supported by the National Natural Science Foundation of China(Nos.60636010,60820106001)
文摘This paper describes a method using both reduced pressure chemical vapor deposition （RPCVD） and ultrahigh vacuum chemical vapor deposition （UHVCVD） to grow a thin compressively strained Ge film. As the first step, low temperature RPCVD was used to grow a fully relaxed SiGe virtual substrate layer at 500 ℃ with a thickness of 135 nm, surface roughness of 0.3 nm, and Ge content of 77%. Then, low temperature UHVCVD was used to grow a high quality strained pure Ge film on the SiGe virtual substrate at 300 ℃ with a thickness of 9 nm, surface roughness of 0.4 nm, and threading dislocation density of - 10^5 cm^-2. Finally, a very thin strained Si layer of 1.5-2 nm thickness was grown on the Ge layer at 550 ℃ for the purpose of passivation and protection. The whole epitaxial layer thickness is less than 150 nm. Due to the low growth temperature, the two-dimensional layer-by-layer growth mode dominates during the epitaxial process, which is a key factor for the growth of high quality strained Ge films.
