Abstract
The quality of germanium (Ge) epitaxial film grown directly on a silicon (Si) (001) substrate with 6° off-cut using conventional germane precursor in a metal organic chemical vapour deposition (MOCVD) system is studied. The growth sequence consists of several steps at low temperature (LT) at 400 °C, intermediate temperature ramp (LT-HT) of ∼10 °C/min and high temperature (HT) at 600 °C. This is followed by post-growth annealing in hydrogen at temperature ranging from 650 to 825 °C. The Ge epitaxial film of thickness ∼ 1 μm experiences thermally induced tensile strain of 0.11 % with a treading dislocation density (TDD) of ∼107/cm2 and the root-mean-square (RMS) roughness of ∼ 0.75 nm. The benefit of growing Ge epitaxial film using MOCVD is that the subsequent III-V materials can be grown in-situ without the need of breaking the vacuum hence it is manufacturing worthy.
Highlights
As the fundamental scaling limits of the silicon (Si) complementary metal-oxide-semiconductor (CMOS) transistors are approached, a paradigm shift has taken place in the industry from dimensional scaling alone to materials innovations
III-V materials have to be integrated onto the Si substrate in order to be compatible with the mainstream CMOS manufacturing
We report the Ge growth directly on Si with 6◦ off-cut toward the [110] by a three-step approach in a metal organic chemical vapour deposition (MOCVD) chamber and the characterization results
Summary
As the fundamental scaling limits of the silicon (Si) complementary metal-oxide-semiconductor (CMOS) transistors are approached, a paradigm shift has taken place in the industry from dimensional scaling alone to materials innovations. III-V materials has been proposed for future high speed and low power computation applications.[1,2,3,4,5,6,7] Si still cannot be replaced by III-V materials because the III-V substrates are expensive and smaller in size due to their brittleness (wafer diameters are typically less than 200 mm). III-V materials have to be integrated onto the Si substrate in order to be compatible with the mainstream CMOS manufacturing. A number of research groups have investigated the III-V growth on Si for optoelectronic and microelectronics applications.[8,9] Direct growth of the III-V materials on Si is challenging due to the large lattice mismatch between these two materials (for example, the mismatch is 4.1% in the case of gallium arsenide (GaAs)). Germanium (Ge) which has a lattice constant that perfectly matches with the GaAs is used to act as a buffer layer between the Si and GaAs.[10,11,12,13]
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