Abstract
The infrared transmission spectrum of Si-doped molecular beam epitaxy (MBE)-grown GaAs epilayers, 2-2.5-mum thick, measured in the oblique (Berreman) geometry, revealed distinct minima in p polarization. Given epilayer thickness < reststrahlen wavelength, the minima are identified as the zone-center transverse optic phonon (omega(TO)) and the high-frequency LO phonon-plasmon coupled mode (omega(+)). Analysis of the experimental data yielded free-carrier concentrations ranging from 2.5x10(17) to 1.4x10(18) cm(-3). The same technique with MBE-grown Si-doped In0.53Ga0.47As epilayers (0.5-1 mum thick) yielded omega(+) modes corresponding to free-carrier concentrations of 8.2x10(16)-2.7x10(19) cm(-3). The observations of the transmission minima in the Berreman geometry and their interpretation demonstrate a direct and simple method for deducing free-carrier concentrations over a wide range.
Published in:
Physical Review B 69,7 (2004) 075314;
Link to original published article:
http://dx.doi.org/10.1103/PhysRevB.69.075314
Keywords
slab including retardation;; optical modes;; oblique-incidence;; raman-scattering;; effective masses;; conduction-band;; semiconductors;; films;; nonparabolicity;; spectroscopy
Date of Version
January 2004
Recommended Citation
Ibanez, J.; Tarhan, E.; Ramdas, A. K.; Hernandez, S.; Cusco, R.; Artus, L.; Melloch, M. R.; and Hopkinson, M., "Direct observation of LO phonon-plasmon coupled modes in the infrared transmission spectra of n-GaAs and n-InxGa1-xAs epilayers" (2004). Department of Physics and Astronomy Faculty Publications. Paper 480.
https://docs.lib.purdue.edu/physics_articles/480