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

3.4 Challenges of Heteroepitaxial Growth of III-V on Silicon
Figure 3.8: Schematic diagram of anti-phase domains boundaries in InAs formed by a
single-atom step on the silicon substrate surface. Figure modied according to reference
[50].
through the growth of compound semiconductor materials on an elemental crystal,
such as the case of InAs/Si, can result in the formation of crystalline subdomains
referred to as anti-phase domains and anti-phase domain boundaries
(APBs) also known as, inversion domains boundaries (IDBs) [31]. There are a
few theoretical reasons for their formation. During growth initiation of a compound
material, two crystal domains can form independently of one another, each
the result of dierent nucleations species like in In vs. As; the planes at which
the domains of reversed polarity meet, referred to as APBs, possess In-In and/or
As-As bonds instead of proper In-As bonds, as in the case of GaP/Si system [49].
In another case, APDs can be formed if the elemental crystal (i.e. silicon) has
single atomic steps on its surface as shown in Fig. 3.8. A surface variation such
as an atomic-level step on the Si substrate can cause the III-V layer above this
step to rotate its orientation, and thus lead to the formation of a propagating
boundary layer between two distinct III-V domains [14].
Due to the lower symmetry of the polar semiconductor, it can grow with
one of two (nonequivalent) crystal orientations on the nonpolar substrate. The
boundaries between regions having these two orientations will also result in the
formation of inverted domain boundaries. The nature of the chemical bonding
across the APBs causes them to be electrically active, which directly relates to
the degradation in material quality. Experiments involving time resolved pho-
43