Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA
Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA
Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA
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3.4 Challenges <strong>of</strong> Hetero<strong>epitaxial</strong> Growth <strong>of</strong> <strong>III</strong>-V on Silicon<br />
Figure 3.4:<br />
Energy gap versus the lattice constant <strong>of</strong> the most common <strong>III</strong>-V <strong>semiconductor</strong>s<br />
in comparison to Si. The indirect <strong>semiconductor</strong> GaP has a lattice constant<br />
almost equal to Si, which is very encouraging for almost lattice matched-heteroepitaxy.<br />
Figure modied according to reference [41].<br />
plotted versus the lattice constant <strong>of</strong> the most common <strong>III</strong>-V <strong>semiconductor</strong>s in<br />
comparison to Si. GaAs as well as InP have a lattice constant larger by more than<br />
4% than that <strong>of</strong> Si. From the values <strong>of</strong> the lattice constants in Table 3.1 one can<br />
calculate the lattice mismatch (f) using Eq. 3.8. Where a S is the lattice constant<br />
<strong>of</strong> the substrate and a L the lattice constant <strong>of</strong> the grown layer [31]. While GaAs<br />
on silicon exhibit a lattice mismatch <strong>of</strong> 4.1 %, InAs on Si suers by a mismatch<br />
<strong>of</strong> 10.4 %.<br />
f = a L − a S<br />
a S<br />
(3.8)<br />
A view at the lattice constants <strong>of</strong> dierent <strong>III</strong>-V compound <strong>semiconductor</strong>s<br />
plotted in Fig. 3.4 reveals that the indirect <strong>semiconductor</strong> GaP has a lattice<br />
constant almost equal to that <strong>of</strong> Si with a lattice mismatch about 0.37 %, which<br />
is very promising for a dislocation free <strong>growth</strong> <strong>of</strong> GaP layers on Si substrates.<br />
The mismatch in Eq 3.8 may take on either sign, with some interesting differences<br />
observed between the tensile strain, when the lattice constant <strong>of</strong> the<br />
epi-layer is less than the lattice constant <strong>of</strong> the substrate (f> 0). On the other<br />
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