Photothermal and optical characterization of intrinsic and Te-doped GaSb
wafers
M.E. Rodríguez1, Rubén Velazquez1,2, I. Rojas1,3, J. García-Rivera1,2, J.G. MendozaAlvarez4
1Centro
de Física Aplicada y Tecnología Avanzada de la UNAM. Juriquilla, Querétaro, México.
en Ciencia e Ingeniería de Materiales, UNAM, México
3Centro de Investigación en Fisica Aplicada y Tecnología Avanzada, IPN, , México D. F. , México
4Departamento de Física, CINVESTAV, México, Av. IPN 2508, México, D.F., México.
5Universidad Tecnológica de Querétaro, Av, Pie de la Cuesta s/n, Querétaro, Qro, México
2Posgrado
Abstract
Photothermal radiometry (PTR) signals obtained with a highly focused laser beam, were used to
obtain PTR amplitude and phase, two-dimensional and three-dimensional thermoelectronic images of
an n-type Gallium Antimony wafer (100) with a diameter of 50.8 mm doped with Tellurium (Te), with a
carrier concentration of 7x1017 cm-3, an EPD < 5 x103 cm-2 from Atramet Inc.USA; and an undoped
GaSb wafer from Firebird semiconductors Ltd., Canada. The frequency chosen to carry out the PTR
images was 10 kHz, corresponding to an optimal difference between the phase and amplitude signals
in the case of the doped GaSb sample. The results indicate that, for the doped sample, the
concentration of Tellurium (Te) is inhomogeneous over the full wafer area because the
thermoelectronic image shows a high plasma component, which is related to the carrier concentration,
at the ends sides of the wafer; meaning that there is a higher Te concentration at the wafer borders.
MicroRaman spectroscopy was used to monitor the presence of Te along the sample; at the center of
the wafer, the -Raman spectra shows a decrease in the Te signal that is related with the Te
concentration. Reflectance images were measured in both samples in order to make corrections in the
PTR signal as result of the changes in the reflectance across the sample.