Reduction of threading dislocation density in Ge/Si using a heavily As-doped Ge seed layer

Abstract

High quality germanium(Ge)epitaxialfilm is grown directly on silicon (001) substrate with 6° off-cut using a heavily arsenic (As) dopedGe seed layer. The growth steps consists of (i) growth of a heavily As-doped Ge seed layer at low temperature (LT, at 400 °C), (ii) Gegrowth with As gradually reduced to zero at high temperature (HT, at 650 °C), (iii) pure Gegrowth at HT. This is followed by thermal cyclic annealing in hydrogen at temperature ranging from 600 to 850 °C. Analytical characterization have shown that the Geepitaxialfilm with a thickness of ∼1.5 µm experiences thermally induced tensile strain of 0.20% with a treading dislocation density (TDD) of mid 106/cm2 which is one order of magnitude lower than the control group without As doping and surface roughness of 0.37 nm. The reduction in TDD is due to the enhancement in velocity of dislocations in an As-doped Gefilm.