Abstract

PEREZ LADRON DE GUEVARA, H.; RODRIGUEZ, A. G.; NAVARRO-CONTRERAS, H.  and  VIDAL, M. A.. Determination of the optical energy gap of Ge_1-xSn_x alloys at 4K. Superf. vacío [online]. 2008, vol.21, n.2, pp.9-11. ISSN 1665-3521.

The optical energy gap of Ge_1-xSn_x alloys (x < 0.14) has been determined from transmittance measurements at 4K using a Fast-Fourier-Transform Infrared Interferometer (FFT-IR) attached to a helium refrigerator. Our results show that the energy gap changes due to the Sn concentration of the alloys. We also show that low temperature increases the energy gap transitions for alloys with low Sn concentrations. By increasing gradually the Sn concentration in alloys the energy gaps decreases, but for x>0.13 alloys, direct energy gap transitions are lower than energy gap obtained at room temperature. These results are according to the theory predicted results at low temperatures.

Keywords : Sputtering; FFT-IR; HRXRD.