In Situ Characterization of Thin Films Utilizing Second Harmonic Generation: Applied Nanotechnology
Translated title
In Situ Characterization of Thin Films Utilizing Second Harmonic Generation
Authors
Sennels, Nicolai ; Buch, Mikkel Aarup
Term
4. term
Education
Publication year
2019
Submitted on
2019-06-09
Pages
106
Abstract
Tynde film er vigtige i mange teknologier, og der er behov for at kontrollere deres egenskaber uden at stoppe processen. Dette projekt undersøger second harmonic generation (SHG), en optisk effekt hvor laserlys omdannes til lys med dobbelt så høj frekvens, som et værktøj til in situ-karakterisering af tynde film. Rapporten gennemgår grundlæggende begreber inden for ikke-lineær optik, SHG, lavenergi-elektrondiffraktion (LEED), optiske parametriske oscillatorer (OPO) og teori om substratoverflader, og den beskriver de anvendte opstillinger, procedurer og software. Som forberedelse til in situ-arbejdet målte vi SHG-signaler fra silicium (Si), silicium med naturlig oxid (Si/SiO2) og hydrogen-terminerede siliciumoverflader. Derefter udførte vi in situ-målinger på sølv (Ag), aluminium (Al) og aluminiumnitrid (AlN) film. For Ag fandt vi en stærk korrelation mellem filmtykkelse og SHG-signalet. For AlN så vi, at SHG-signalet korrelerer med krystallinitet (hvor ordnet krystalstrukturen er). På baggrund af disse resultater skitserer vi et design til et industrielt SHG-setup.
Thin films are important in many technologies, and there is a need to check their properties without stopping the process. This project investigates second-harmonic generation (SHG), an optical effect that converts laser light into light at twice its frequency, as a tool for in situ characterization of thin films. The report reviews basic concepts in nonlinear optics, SHG, low-energy electron diffraction (LEED), optical parametric oscillators (OPO), and substrate surface theory, and it describes the experimental setups, procedures, and software used. As preparation for in situ work, we measured SHG signals from silicon (Si), silicon with a native oxide (Si/SiO2), and hydrogen-terminated silicon surfaces. We then performed in situ measurements on silver (Ag), aluminum (Al), and aluminum nitride (AlN) films. For Ag, we found a strong correlation between film thickness and the SHG signal. For AlN, we observed that the SHG signal correlates with crystallinity (how ordered the crystal structure is). Based on these findings, we outline a design for an industrial SHG setup.
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