Tensile-strained nanoscale Ge/In0.16Ga0.84As heterostructure for tunnel field-effect transistor.

Tensile strained Ge/In0.16Ga0.84As heterostructure was grown in situ by molecular beam epitaxy using two separated growth chambers for Ge and III-V materials. Controlled growth conditions led to the presence of 0.75% in-plane tensile strain within Ge layer. High-resolution transmission electron microscopy confirmed pseudomorphic Ge with high crystalline quality and a sharp Ge/In0.16Ga0.84As heterointerface. Atomic force microscopy revealed a uniform two-dimensional cross-hatch surface morphology with a root-mean-square roughness of 1.26 nm. X-ray photoelectron spectroscopy demonstrated reduced tunneling-barrier-height compared with Ge/GaAs heterostructure. The superior structural properties suggest tensile strained Ge/In0.16Ga0.84As heterostructure would be a promising candidate for high-performance and energy-efficient tunnel field-effect transistor applications.