Caracterizacion por fotorreflectancia de películas epitaxiales cuaternarias Ga1-xInxAsySb1-y
...
Marín Hurtado, Jorge Iván | 2004-09-23
Three Ga1¡xInxAsySb1¡y epitaxial thin films samples: x = 0:16; y = 0:11, x = 0:17; y =
0:14 and x = 0:17; y = 0:18, respectively, were studied by means of photoreflectance
(PR) technique in order to determine the fundamental band-gap E0 at temperature
ranging from 12 to 250K. The samples were grown by liquid phase epitaxy (LPE) on
GaSb : Te (100) substrates. The PR spectra allow identify a high quality quaternary
thin films. These spectra are well-described by a single third derivate lorentzian form
(TDLF) related to a 3DM0 critical point with a low broadening parameter (6¡8meV ).
For the Ga0:83In0:17As0:14Sb0:86 sample, the PR spectra shows two lineshapes at low temperatures
which disappear at increasing temperature. This behavior is explained by the
degeneration of valence band induced by internal strain due to lattice deffects. The temperature
dependence of band-gap energy were fitted to Varshni, Vi˜na and Manoogian-
Wolley (M-W) expressions founding, at low temperatures, a best fitting with Vi˜na and
M-W models. Finally, from the temperature dependence of broadening parameter, we
found a phonon temperature closed to mixed-mode GaSb+InAs LO phonon frequencies
measured to GaInAsSb/GaSb by Raman spectroscopy. These values agree to phonon
temperatures obtained by Vi˜na and M-W models.
LEER