Remote, Non-invasive, Optical Method of Temperature Detection
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The focus of this thesis is the development of a remote, optically based, noninvasive, large working distance Raman method of temperature detection that relies upon observing the temperature-dependent phonon redshift. The method was applied to detect in-situ temperatures of a molecular beam epitaxy (MBE) system’s sample manipulator during a standard ramp process. The development process entailed calibrating measurements of the E2 Raman peak of test subject 6H-SiC with thermocouple temperatures in a standard laboratory setting and at two known melting points, In and InSb, in the MBE chamber. A key part of this method’s development was designing an apparatus capable of acquiring Raman spectra at the sample-optical port separation distance found in the MBE chamber. Available capabilities permitted the qualification of this approach from room temperature to 527 °C. Comparing the redshift predicted by the combined effects of thermal expansion and anharmonic phonon decay with the calibration data yielded fit parameters that are in good agreement with what has been previously reported. Results show that the thermocouple significantly overestimates the substrate temperature by approximately 100 °C and that there is a > 10 min delay in achieving steady state at the sample relative to the controller.