No abstract

We investigate the growth performance of tin oxide on the Si substrate, achieved by spray pyrolysis using the sensitive analysis techniques X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). These complementary techniques confirm the growth of homogeneous SnO2 thin films. We also study the electronic distribution of the valence band of SnO2 theoretically using density functional theory (DFT). The chemical and physical properties of the material depend on the electron structure varying as a function of energy. The density of states (DOS) is calculated using the modified Becke–Johnson-Generalized Gradient Approximation (mBJ-GGA) in order to identify the electronic orbitals and the importance of their contribution to the electronic structure of the valence band. Furthermore, we use the experimental technique UV Photoelectron Spectroscopy (UPS) for studying the electronic distribution within the valence band and for validating the theoretical results of the density of states of SnO2/Si.

The chemical composition, crystalline structure and optical properties of un-doped ZnO (UZO) and indium (6%)-doped ZnO (IZO) thin films grown on Si substrate were studied using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and photoluminescence (PL) techniques. The results are complementary and confirm each other. The surface is cleaned using checked ultra-high vacuum (UHV) treatment (argon ion sputtering followed by successive heating). For IZO, the XPS analysis displays that the indium incorporates in the ZnO matrix to form the In-O-Zn-type chemical bonds. The PL of UZO reveals structural defects, including oxygen interstitial (O[Formula: see text], oxygen vacancies (V[Formula: see text], zinc vacancies (V[Formula: see text] and interstitial zinc (Zn[Formula: see text], and they decrease with the In doping and UHV treatment. For IZO, the PL measurements show the great interest of UHV treatment to stimulate the incorporation of indium into the ZnO matrix. There is an increase in the UV emission intensity and improvement of its physical structure. The In (6%) doping of ZnO is convenient to compensate the zinc vacancies (V[Formula: see text], eliminate Zni and VO, and ensure the structural homogeneity of IZO film. All the detected peaks of the XRD patterns are matched to the wurtzite crystalline structure for both UZO and IZO thin films grown mainly along the (002) orientation plane.

In this study, we use complementary and sensitive experimental techniques XPS (X-rays Photoelectron Spectroscopy), AES (Auger Electron Spectroscopy, REELS (Reflection Electron Energy-Loss Spectroscopy) and PL (photoluminescence) to investigate and compare the chemical, structure, electronic and optical properties of Un-doped ZnO (UZO) and Indium-doped ZnO (IZO) (4% In; 6% In) thin films. Spray method is used for the growth of these thin films on Si substrate. A treatment process UHV (Ultra-High -Vacuum: Ar+ sputtering followed by checked successive heating until 650°C) is performed. XPS and AES results allow to confirm the clean state of samples and the incorporation of indium into the ZnO matrix to form chemical species of (In-O-Zn) type. The recorded REELS spectra at different primary energies and the PL measurements justify that the UHV treatment plays an important role to improve the physical structure of IZO (6% In).