Cdte- based compunds growth by vapor phase techniques

Resum

The aim of this thesis is a better understanding of the properties of polycristalline CdTe to further implement its industrial applications. Also the role of some dopants such as: Ge, Bi, Yb and Zn in the improvement of material properties were studied. Another fundamental aspect studied in this work is to obtain semi-insulating crystals with optimal transport charge properties. The control of the resistivity of CdTe is an exceedingly difficult task, and depends on donor dopant selection to compensate exactly the acceptor impurities and defects present in the material. The most interesting contribution studied in this field is the use of Bi as dopant for semi-insulating CdTe, which has very high photosensitivity and excellent properties of charge transport. We show that heating the samples, notably improves both its crystalline quality and its surface morphology. These facts that allows significantly reducing the typical concentration of native and foreign defects. Also, special attention is paid to the technological process to achieve the optimal dry etching conditions suitable for CdTe- based waveguides, as well as, to the growth of CdZnTe films into nanoporous alumina. The formation of Cd(Zn)Te crystalline columnar nanostructures may be very attractive for the fabrication of micropixels suitable for further development of X-and ¿-ray high resolution imaging devices. Finally, we report on theoretical and experimental results on the use of CdTe and Cd(Zn)Te as core materials for the development of all- optical photonic devices. This idea of using (CdTe compounds) Cd(Zn)Te as optical material for implementation of highly dense all- optical photonic integrated circuits is intended to overcome the limitations in terms of nonlinear interaction that occurs in Si (mainly, the high values of two-photon absorption (TPA) and the induced free-carried absorption) whilst preserving the main advantages of the Silicon-on-insulator, SOI- based photonic technology: high index contrast (small size of the photonic components) and manufacturability with CMOS tools and process (which ensures large scale fabrication and low cost of manufacturing).