Semiconductor physics and light-matter interaction
PHYS-433
Recorded version of Lecture 4 Part 1
PHYS-433 Lecture 4 part 1
13.10.2021, 13:39
This week, we cover the important notion of strain and its impact on the band structure of semiconductors. To this end, we introduce the notion of epitaxy and more precisely heteroepitaxy that generate the accumulation of strain energy due to the lattice-mismatch between the substrate and the newly grown epilayers. This situation is very general and can be met, e.g., when growing quantum heterostructures. To avoid plastic relaxation and the formation of extended defects such as dislocations, the notion of critical thickness is introduced. The out of plane deformation is derived for 2D epilayers by making use of Hooke's law that links the tensor of deformations to the tensor of stress via the elastic constants. This allows to connect the critical thickness to the out of plane deformation. Examples are given in the framework of cubic crystals that is representative of diamond and zinc-blende structures. The case of the shift experienced by the conduction band and valence band energy levels close to the band gap is documented when applying hydrostatic deformation and shear strain in the case of zinc-blende semiconductors. Finally, experimental setups allowing to explore hydrostatic deformation and biaxial strain are briefly discussed.
PHYS-433 Lecture 4 part 1
13.10.2021, 13:39
This week, we cover the important notion of strain and its impact on the band structure of semiconductors. To this end, we introduce the notion of epitaxy and more precisely heteroepitaxy that generate the accumulation of strain energy due to the lattice-mismatch between the substrate and the newly grown epilayers. This situation is very general and can be met, e.g., when growing quantum heterostructures. To avoid plastic relaxation and the formation of extended defects such as dislocations, the notion of critical thickness is introduced. The out of plane deformation is derived for 2D epilayers by making use of Hooke's law that links the tensor of deformations to the tensor of stress via the elastic constants. This allows to connect the critical thickness to the out of plane deformation. Examples are given in the framework of cubic crystals that is representative of diamond and zinc-blende structures. The case of the shift experienced by the conduction band and valence band energy levels close to the band gap is documented when applying hydrostatic deformation and shear strain in the case of zinc-blende semiconductors. Finally, experimental setups allowing to explore hydrostatic deformation and biaxial strain are briefly discussed.
PHYS-433 Lecture 4 part 1
13.10.2021, 13:39
This week, we cover the important notion of strain and its impact on the band structure of semiconductors. To this end, we introduce the notion of epitaxy and more precisely heteroepitaxy that generate the accumulation of strain energy due to the lattice-mismatch between the substrate and the newly grown epilayers. This situation is very general and can be met, e.g., when growing quantum heterostructures. To avoid plastic relaxation and the formation of extended defects such as dislocations, the notion of critical thickness is introduced. The out of plane deformation is derived for 2D epilayers by making use of Hooke's law that links the tensor of deformations to the tensor of stress via the elastic constants. This allows to connect the critical thickness to the out of plane deformation. Examples are given in the framework of cubic crystals that is representative of diamond and zinc-blende structures. The case of the shift experienced by the conduction band and valence band energy levels close to the band gap is documented when applying hydrostatic deformation and shear strain in the case of zinc-blende semiconductors. Finally, experimental setups allowing to explore hydrostatic deformation and biaxial strain are briefly discussed.
PHYS-433 Lecture 4 part 1
13.10.2021, 13:39
This week, we cover the important notion of strain and its impact on the band structure of semiconductors. To this end, we introduce the notion of epitaxy and more precisely heteroepitaxy that generate the accumulation of strain energy due to the lattice-mismatch between the substrate and the newly grown epilayers. This situation is very general and can be met, e.g., when growing quantum heterostructures. To avoid plastic relaxation and the formation of extended defects such as dislocations, the notion of critical thickness is introduced. The out of plane deformation is derived for 2D epilayers by making use of Hooke's law that links the tensor of deformations to the tensor of stress via the elastic constants. This allows to connect the critical thickness to the out of plane deformation. Examples are given in the framework of cubic crystals that is representative of diamond and zinc-blende structures. The case of the shift experienced by the conduction band and valence band energy levels close to the band gap is documented when applying hydrostatic deformation and shear strain in the case of zinc-blende semiconductors. Finally, experimental setups allowing to explore hydrostatic deformation and biaxial strain are briefly discussed.
PHYS-433 Lecture 4 part 1
13.10.2021, 13:39
This week, we cover the important notion of strain and its impact on the band structure of semiconductors. To this end, we introduce the notion of epitaxy and more precisely heteroepitaxy that generate the accumulation of strain energy due to the lattice-mismatch between the substrate and the newly grown epilayers. This situation is very general and can be met, e.g., when growing quantum heterostructures. To avoid plastic relaxation and the formation of extended defects such as dislocations, the notion of critical thickness is introduced. The out of plane deformation is derived for 2D epilayers by making use of Hooke's law that links the tensor of deformations to the tensor of stress via the elastic constants. This allows to connect the critical thickness to the out of plane deformation. Examples are given in the framework of cubic crystals that is representative of diamond and zinc-blende structures. The case of the shift experienced by the conduction band and valence band energy levels close to the band gap is documented when applying hydrostatic deformation and shear strain in the case of zinc-blende semiconductors. Finally, experimental setups allowing to explore hydrostatic deformation and biaxial strain are briefly discussed.
PHYS-433 Lecture 4 part 1
13.10.2021, 13:39
This week, we cover the important notion of strain and its impact on the band structure of semiconductors. To this end, we introduce the notion of epitaxy and more precisely heteroepitaxy that generate the accumulation of strain energy due to the lattice-mismatch between the substrate and the newly grown epilayers. This situation is very general and can be met, e.g., when growing quantum heterostructures. To avoid plastic relaxation and the formation of extended defects such as dislocations, the notion of critical thickness is introduced. The out of plane deformation is derived for 2D epilayers by making use of Hooke's law that links the tensor of deformations to the tensor of stress via the elastic constants. This allows to connect the critical thickness to the out of plane deformation. Examples are given in the framework of cubic crystals that is representative of diamond and zinc-blende structures. The case of the shift experienced by the conduction band and valence band energy levels close to the band gap is documented when applying hydrostatic deformation and shear strain in the case of zinc-blende semiconductors. Finally, experimental setups allowing to explore hydrostatic deformation and biaxial strain are briefly discussed.