Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA

Chapter 7
Optimization of MEE and MBE
growth of GaP Buer on Silicon
Substrate
7.1 Overview
Gallium phosphide (GaP) is considered as the best candidate among III-V to be
rstly grown on silicon. This is due to the smallest lattice mismatch of 0.37 %
compared to any other III-V/Si combinations. The lattice constant is the single
most important parameter to consider when choosing a material for heteroepitaxial
growth. If the mismatch is too large or the growth conditions not appropriate,
dislocations will be formed, which strongly degrades the material quality and
device performance. GaP has long been considered the most promising III-V
material for direct integration on Si substrates. However, detailed studies of the
initial stages of GaP-on-Si (001) growth using RHEED and high-resolution electron
microscopy showed that, similar to GaAs/Si, the main problem here is to
obtain a continuous planar perfect GaP layer because the nucleation occurs by
the VW growwth mechanism, i.e., the process involves the formation of separate
large-sized islands whose coalescence gives rise to defects with high densities. A
number of research activities and studies relevant to the understanding of GaPon-Si
(001) growth and its challenges were reported [123, 124, 125]. Hence one
of the key advantages for III-V/Si integration via GaP is that there should be
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