Abstract
In this article, I report in-situ thin film growth and etching measurement and control with ultra high precision. A stack of thin film layers of AlAs/Al 0.1Ga 0.9As to form Bragg reflector for the surface emitting semi-conductor laser was grown by gas source molecular beam epitaxy on a rotating wafer and the growth process was monitored with inclined incident polarized He–Ne laser light reflectance measurement. The multiple thin film layers were preferred to increase the visibility of the oscillating intensity variation signal for feasibility experiments. The inferred growth rate from the reflectance analysis was found to be 0.15 nm/s which remained in agreement with set growth parameters. The laser light reflectance analysis method was also employed for in-situ control and measurement of thin film etching process. The inferred etching rate was found to be 0.75 nm/s by the chemical etchant H 3PO 4:H 2O 2:H 2O::3:1:100. Calibrated optical reflectance signal for growth and etching process is proposed for measuring and control their respective thickness and depth with very high accuracy and precision.
Published Version
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