Presentation Information
[23a-22A-5]Effect of Si cap layer on the lattice strain in a Ge wire structure on Si
Joshua Chombo1, 〇FAIZ FAIZ MOHD1, Takeshi Hizawa1, Jose A. Piedra-Lorenzana1, Keisuke Yamane1, Mingjun Jiang2, Donghwan Ahn2, Kazumi Wada3, Yasuhiko Ishikawa1 (1.Toyohashi Univ. Tech., 2.Kookmin Univ., 3.MIT)
Keywords:
Germanium,Strain,Silicon cap
A Ge epitaxial layer on Si has been considered a prospective material for light-emitting devices in Si photonics. Tensile lattice strain in Ge, induced by the thermal expansion mismatch with Si, plays an essential role in efficient direct-gap light emission because of the reduction in the energy offset between the direct Γ and indirect L valleys in the conduction band. In a Ge wire structure as narrow as 1 µm or below, the tensile strain is unfavorably relaxed due to the edge-induced relaxation, whereas we have recently reported the successful anti-relaxation by applying a Si cap layer to entirely embed the Ge wire structure. However, such an anti-relaxation was effective only for the trench-filling structure, i.e., for the non-trench-filling (mesa-shaped) Ge, an unexpected compressive strain was induced. Here, the mechanism is studied to explain the unexpected compressive strain.