28 June 2015 to 3 July 2015
Africa/Johannesburg timezone
SAIP2015 Proceeding published on 17 July 2016

Investigating charge carrier effects in silicon membranes using fs laser.

1 Jul 2015, 16:10
1h 50m
Board: C.186
Poster Presentation Track C - Photonics Poster2

Speaker

Mr Wilfrid Ndebeka (Laser Research Institute, Stellenbosch University)

Abstract content <br> &nbsp; (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>

The second harmonic (SH) generated at the Si/SiO2 interface varies on a time scale of several seconds when illuminated with high intensity near infrared laser pulse (λ = 800 nm, with 80 MHz frequency, Epulse ≤ 10 nJ). The temporal behaviour arises from generation of trap sites and subsequent trapping of charges at the interface via multi-photon processes. These trapped charges create an interfacial electric field which influences the nonlinear properties of the Si/SiO2 interface and leads to a time dependent second harmonic (TDSH) signal on continuous irradiation. This is known as electric field induced second harmonic (EFISH) generation. In this work, measurements are focused on the simultaneous measurements of EFISH signal from a free standing oxidized Si membrane both in reflection and transmission as a function of the irradiation time. Results show that the transmission of the fundamental irradiation as well as the transmitted SH signal generated from the Si membrane increases, reaches a maximum, and then decreases again as the input intensity is increased. The nonlinear behaviour of the transmitted signal is explained using free charge carrier absorption (FCA) in silicon.

Level for award<br>&nbsp;(Hons, MSc, <br> &nbsp; PhD, N/A)?

PhD

Please indicate whether<br>this abstract may be<br>published online<br>(Yes / No)

Yes

Apply to be<br> considered for a student <br> &nbsp; award (Yes / No)?

yes

Main supervisor (name and email)<br>and his / her institution

Erich Rohwer, egr@sun.ac.za

Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?

yes

Primary author

Mr Wilfrid Ndebeka (Laser Research Institute, Stellenbosch University)

Co-authors

Dr Christine Steenkamp (Laser Research Institute, Stellenbosch University) Prof. Erich Rohwer (Laser Research Institute, Stellenbosch University) Prof. Herbert Stafast (Leibniz Institute of Photonic Technology, Jena, Germany) Dr Pieter Neethling (Laser Research Institute, Stellenbosch University)

Presentation Materials

There are no materials yet.