Deposition of SnO2 and GaAs thin films, and building of devices based on the heterojunction SnO2/GaAs/insulating layer.

Abstract

The work involves the production and the electrical and optical characterization of thin films in different stages. Step 1) Deposition of SnO2 and GaAs, and heterojunction GaAs/SnO2: a) SnO2 doped with rare-earth ions, deposited via sol-gel-dip-coating, b) GaAs. It will be done the incorporation of the rare-earth dopant in the semiconductor matrix oxide (SnO2), where they present high emission efficiency, and combination of SnO2 with a high electron mobility semiconductor (GaAs), to separate electron scattering centers (ionized rare earth ions) from the region of electrical transport. The photo-induced investigation of electrical interface between the semiconductors will be critical at this stage. Step 2) deposition of a insulating layer, which must be of alumina (Al2O3), but can also be silica (SiO2). The goal here is to obtain knowledge for making a transparent field effect transistor where on the heterojunction SnO2/GaAs, an insulating layer is deposited, preferably Al2O3, which exhibites high dielectric constant and low leakage current. The GaAs layer must be deposited by resistive evaporation technique, but can also be used commercial substrates or material obtained by more sophisticated techniques such as MBE. The rare-earth dopant to be used is Eu3 +, with emission in the red, and / or Er3+, with emission in the near infrared. It will be analyzed the conditions of deposition and the electrical characteristics of the films, especially with regard to the photo-induced electrical transport of heterojunction. The measurements to be carried out in step 1 include: resistivity as a function of temperature, optical absorption in the UV-Vis and FTIR, X-ray diffraction, capacitance, scanning electron microscopy to evaluate the interfaces substrate/SnO2, substrate / GaAs and SnO2/GaAs, since the interfacial conduction channel is a fundamental parameter for the transport properties. In step 2, where the insulating layer is deposited, it will be investigated the conditions of longitudinal and transverse (leakage current) transport in the built device (transparent field effect transistor). It will also be provided an analysis of the emission control of rare-earth ion from the modulation of conduction channel in the device. The main objective is the development of scientific and technological knowledge, and contribution to the making of electroluminescent devices and / or transparent transistors, with high electron mobility.