Authors: A. Ouerdane, M. Bouslam, M. Ghaffour, A. Abdellaoui, C. Jardin
Affilation: Centre Universitaire Khemis Miliana, American Samoa
Pages: 249 - 252
Keywords: AES, EELS, casino, SEM, ZnO/InP, solar cells
Abstract: ZnO is a metallic oxide ,its electrical resistivity (10--5Ωcm) and its high transmittance (80–90%) in the visible range give it a particular importance as electrode for photovoltaic conversion in solar cells. In the ten recent years many researches are focused on ZnO because of the abundance of its components in nature, its non toxicity and the wide range of its electrical resistivity which can extend from 10*4to 10*12Ωcm. ZnO is an n-type semiconductor. Others authors have reported the preparation of p-type ZnO films It crystallizes in the wurtzite hexagonal structure with of wide gap equal to 3.2 eV. Our purpose is to study the effects of electron beam bombardment on the thin films ZnO grown on the substrates lnP (100), by using Auger Electron Spectroscopy (AES) and Electron Energy loss Spectroscopy (EELS) associated to the simulation scanning program CASINO. We find that the materials InP (100) gives rise successively to a foil of oxide when ZnO/lnP(100) seems to be unchanged. The Monte Carlo simulation Casino is used to scan the distribution and confirms these results. We show that ZnO/lnP (100) surface is very resistant to the electron beam irradiation when compared to the InP one. Its X-ray intensity, computed by Casino program, varies weakly with the electron beam energy when in InP its variation is important. Experimental and simulated methods allow us to conclude that ZnO/lnP thin film seems to be not subjected to a charge effect when InP surface strongly ones. Electron beam irradiation on ZnO/InP By irradiating ZnO/InP (100) by the electron beam of 4 keV energy, we observe the structure and location of Auger signal 0-KLL which remains unchanged as function of applied potential to the surface The ZnO/InP does not seem to be subjected to a charge effect. This result might be of great importance because it is known that InP (100) irradiated by the electron beam is subjected to charge effect Casino simulation In this section we use a code simulating the trajectory of electrons in a solid. It is known that the excess energy due to the electron beam bombarding a material target is released in the form of electromagnetic radiation (X-rays) or kinetic energy to the bulk atomic electrons. The inelastic interaction gives rise to a wide variety of signals such as X-rays; the secondary electron emission, electrons. We use the CASINO simulation; this program is specially designed for low beam interaction in a bulk and thin foil. It can be used to generate many of the recorded signals (X-rays and backscattered electrons) in a scanning electron microscope. Other result of the beam electron bombardment is the carrier screening of the internal electric field commonly named the space charge effect. On fig 3(i) we see a surface profile of ZnO/InP as Casino scanning result. On fig.3(ii) we record, for the two compounds InP and ZnO/InP, the variation of the X-Ray intensity as function of the electron beam energy. The InP intensity varies strongly, with the incident electron beam energy while the X-Ray intensity of ZnO/InP does not seems one.