nl9b04272_si_001.pdf (1.47 MB)
Unpredicted Internal Geometric Reconfiguration of an Enclosed Space Formed by Heteroepitaxy
journal contribution
posted on 2019-12-13, 19:23 authored by Rui-Tao Wen, Baoming Wang, Jurgen MichelEpitaxial lateral overgrowth (ELO) over a free-standing
dielectric
mask is an unexplored territory in selective epitaxy growth (SEG)
of semiconductors. By shrinking the dielectric mask dimension to the
micron scale, the growth fronts from ELO are able to converge and
coalesce, thus providing the freedom to engineer the interfacial structure
between the epi-layer and dielectric mask. We demonstrate, herein,
anomalous adatom diffusion and migration at the Ge/SiO2 interface upon SEG on a Si (100) wafer. We find, depending on the
oxide strip length, a polyhedral cavity or tunnel can form on the
oxide layer. More importantly, we observe a thermally induced substantial
internal surface reconfiguration process of Ge atoms that connects
two tunnels and one cavity in order to form a single tunnel. Defect-free
Ge above the oxide strips is obtained after coalescence. Our findings
yield new insight into adatom migration in an enclosed space, and
the cavity and tunnel show the first known three-dimensional geometric
configuration in selective heteroepitaxial structures.