Strain dependence of second-harmonic generation in silicon.

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Physics

Background:

• Strained silicon exhibits a non-centrosymmetric lattice, unlike ordinary silicon.
• This unique structure enables nonlinear optical processes, specifically those involving second-order nonlinear susceptibility.
• Applications in microelectronics and integrated optics are emerging for strained silicon.

Purpose of the Study:

• To investigate the dependence of nonlinear susceptibility on applied strain in silicon.
• To compare experimental results with theoretical predictions for strained silicon.

Main Methods:

• Utilized reflected second-harmonic generation, a surface-sensitive technique.
• Investigated bulk silicon strained by a thermal oxide layer.
• Compared experimental stress-susceptibility data to an analytical model of deformed silicon orbitals.

Main Results:

• Established a quantifiable relationship between applied stress and nonlinear susceptibility enhancement in strained silicon.
• Demonstrated the suitability of reflected second-harmonic generation for studying strained silicon.
• Validated experimental findings against theoretical predictions.

Conclusions:

• The stress-susceptibility dependence in strained silicon is experimentally determined and theoretically supported.
• This understanding is crucial for developing photonic devices leveraging second-order nonlinear optical processes in silicon.
• Strained silicon offers significant potential for advanced optical applications.