Abstract
The work involves the deposition, characterization, and conbination in the form of heterostructures, of some types of semiconductor thin films, obtained by means of resistive evaporation and sol-gel dip-coating techniques. This combination of techniques and films has three key aspects: 1) deposition of GaAs and AlAs by resistive evaporation technique, which will be studied individually or combined in the form of heterostructures. 2) combination of these semiconductors with an oxide semiconductor (SnO2), deposited by sol-gel-dip-coating, aiming to separate electron scattering centers (ionized rare-earth ions) from the region of electrical transport, 3) incorporation of rare-earth ions Ce3 + and / or Er3+, in the matrix of the oxide semiconductor, where they exhibit high emission efficiency. 4) Combination of SnO2 with TiO2. For the combination of SnO2 with III-V semiconductors, may also be used GaAs films deposited by other techniques, especially sputtering. It will be analyzed the conditions of deposition and the electrical and optical characteristics of the films, especially with regard to electrical transport of heterojunctions of GaAs / AlAs, GaAs/SnO2 and SnO2/TiO2, because the interfaces can provide transport characteristics that increase electrical conductivity. Measurements to be carried out include: resistivity and current-voltage as a function of temperature, optical absorption of UV to infrared, X-ray diffraction and scanning electron microscopy to evaluate the interfaces substrate/SnO2, SnO2/GaAs, GaAs / AlAs and SnO2/TiO2, since the interfacial conduction channel is a fundamental parameter for the transport properties. Aiming to further explore the properties of these heterojunctions interface, it will be performed experiments of optical excitation of films generating electrical signal and also optical emission. The project includes an instrumentation step, where the student will be responsible for building a sample holder for electrical connection between sample and equipment outside the cryostat, aiming to simplify a crucial problem for performing electrical measurements. The main objective is the development of scientific and technological knowledge, with a view to making future devices.
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