210
7 Structuring Possibilities
Fig. 7.1 Band gap as a function of the in-plane lattice parameter. The common semiconductor
materials in this range are the wurtzite-like nitrides. Remarkably, some sulfur-based TMDCs such
as WS 2 and Mo 2 have a very similar lattice parameter among themselves and are almost matched
to GaN. Other transition-metal diselenides feature a wider lattice, e.g. TiS 2 is in principle latticematched to a GaInN. Similarly, the transition-metal diselenides lie closely together. For a more
elaborate depiction of the alloy lines between GaN, AlN and InN, and the relation/comparison
to other typical semiconductor systems (many of them zinc-blende type and with larger lattice
parameter), the interested reader is referred to semiconductor physics textbooks. The insulating
hBN with band gap of about 5–6 eV and a lattice constant of about 0.25 nm does not fit into
this chart’s range. The rainbow-coloured box indicates the visible spectral region. Reproduced
under the terms of the CC-BY Creative Commons Attribution 4.0 International Licence (http://
creativecommons.org/licenses/by/4.0/). [4] Copyright 2016 The Author(s), published by Springer
Nature
top of each other. Of course, techniques have been developed to counter the influence
of lattice mismatch, for instance by introducing strain compensating layers.
Nowadays, with the revival of studies on 2D materials, which may one day become
part of integrated circuits or semiconductor optoelectronic devices, they are eagerly
integrated into the existing epitaxy map of conventional semiconductors. This is
pursued with eyes towards van-der-Waals (vdW) epitaxy, i.e. the controlled growth
of vertical stacks based on layered materials. For such a map including TMDCs
1
(Fig. 7.1), see for instance [4], in which TMDCs are discussed as a substrate material
for crystalline GaN growth.
As a general rule, one can say that for optoelectronic applications very high-quality
materials are usually required, because charge carriers recombine nonradiatively at
defects—unless the defects are rather a feature than a bug. These quality-crystalline
1 Acronym for transition-metal dichalcogenides.
7 Structuring Possibilities
Fig. 7.1 Band gap as a function of the in-plane lattice parameter. The common semiconductor
materials in this range are the wurtzite-like nitrides. Remarkably, some sulfur-based TMDCs such
as WS 2 and Mo 2 have a very similar lattice parameter among themselves and are almost matched
to GaN. Other transition-metal diselenides feature a wider lattice, e.g. TiS 2 is in principle latticematched to a GaInN. Similarly, the transition-metal diselenides lie closely together. For a more
elaborate depiction of the alloy lines between GaN, AlN and InN, and the relation/comparison
to other typical semiconductor systems (many of them zinc-blende type and with larger lattice
parameter), the interested reader is referred to semiconductor physics textbooks. The insulating
hBN with band gap of about 5–6 eV and a lattice constant of about 0.25 nm does not fit into
this chart’s range. The rainbow-coloured box indicates the visible spectral region. Reproduced
under the terms of the CC-BY Creative Commons Attribution 4.0 International Licence (http://
creativecommons.org/licenses/by/4.0/). [4] Copyright 2016 The Author(s), published by Springer
Nature
top of each other. Of course, techniques have been developed to counter the influence
of lattice mismatch, for instance by introducing strain compensating layers.
Nowadays, with the revival of studies on 2D materials, which may one day become
part of integrated circuits or semiconductor optoelectronic devices, they are eagerly
integrated into the existing epitaxy map of conventional semiconductors. This is
pursued with eyes towards van-der-Waals (vdW) epitaxy, i.e. the controlled growth
of vertical stacks based on layered materials. For such a map including TMDCs
1
(Fig. 7.1), see for instance [4], in which TMDCs are discussed as a substrate material
for crystalline GaN growth.
As a general rule, one can say that for optoelectronic applications very high-quality
materials are usually required, because charge carriers recombine nonradiatively at
defects—unless the defects are rather a feature than a bug. These quality-crystalline
1 Acronym for transition-metal dichalcogenides.