Characterization of laser deposited CdTe and Hg1-xCdxTe thin films

CdTe and Hg1-xCdxTe narrow-gap semiconductor materials were deposited as thin films on optical glass, by the laser-assisted physical vapor deposition (LAPVD) process. A pulsed CO2-TEA laser was used to vaporize the studied materials in a vacuum chamber. The Fourier analysis of the (111) CdTe X-ray diffraction profile was used to determine the average effective crystallite size, the root mean square of the microstrain, the stacking fault probability within the crystallites and the dislocation density for CdTe films of various thicknesses. The X-ray diffraction pattern of the Hg1-xCdxTe films contains (100) reflection, indicating highly textured films with [100] direction of the HgTe type structure. Photoacoustic (PA) measurements were done to establish the absorption edge of the CdTe and Hg1-xCdxTe thin films. The PA spectra were fitted with an exponential function obtaining 1.45 eV absorption threshold photon energy for CdTe films and around 0.3 eV for Hg1-xCdxTe, which corresponds to a x = 0.3 alloy fractional composition.