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Measurements of optical properties of bulk and thin film semiconductors using the PDS technique

University of British Columbia

Photothermal deflection spectroscopy (PDS) was used to measure the bandgap optical parameters and the Urbach energy of semi-insulating (SI) GaAs and a 238nm GaNAs epitaxial thin film in the energy range 800-1l00nm. To do so, a PDS apparatus was setup using a 0.lmW and l0nm bandwidth pump beam obtained with a f/3.8 monochromator and a 150W Tungsten Halogen lamp, a HeNe laser for the probe beam, CCI[superscript omitted] for the deflecting medium and a linear position sensitive detector. The spectra obtained for GaAs and GaNAs were compared with models based on the Rosencwaig-Gersho and the Fernelius theories of ID heat diffusion which consider absorption in respectively one and two sample layers, and also on a model of absorption based on literature results. Preliminary results indicate that more work will be needed on the apparatus/models to qualify the validity of the fitted optical parameters. The PDS apparatus demonstrated an absorbance sensitivity limit of ~10[superscript omitted] with the samples investigated.

Text

2011-03-15

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http://hdl.handle.net/2429/32465

Physics

University of British Columbia

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