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Technology of oxides ZnO, Cu2O, SiO2 obtaining with photon annealing for semiconductor devices


Author: Oleg Lupan
Degree:doctor of engineering
Speciality: 05.27.01 - Solid State Electronics, Microelectronics and Nanoelectronics
Year:2005
Scientific adviser: Sergiu Şişianu
doctor, associate professor (docent), Technical University of Moldova
Institution:

Status

The thesis was presented on the 13 September, 2005
Approved by NCAA on the 27 October, 2005

Abstract

Adobe PDF document – 1.06 Mb / in romanian

Keywords

ZnO, Cu2O, SiO2, photon annealing, chemical deposition, anodical growth, rapid photothermal processing, thin films, gas sensor

Summary

The author's scientific investigations presented in the dissertation concern the results of elaborated technology with chemical deposition and rapid photon annealing for ZnO, Cu2O and SiO2 films obtaining for semiconductor devices – gas sensors and MOS (Al/SiO2/Si ) – structures with high efficiency, short duration, energy save, accessible auxiliary materials and nonsophisticated equipment.

There are presented the investigation results of ZnO films doped with Sn, Al, Cu, Pd for the first time obtained by successive ionic layer adsorption and reaction SILAR method under UV irradiation and rapid photothermal processing RPP. There are shown the optimal concentrations of the cations complex solution (0.04, 0.08, 0.12 and 0.15M) and the impurity content (4-10at%).

The optimal regimes of the rapid photothermal processing RPP for the control of parameters and characteristics of the ZnO (500-650°C, 10-40s), Cu2O (250-350°C, 7-10s) and SiO2 (450- 600°C, 15-30s) films have been determined and applied.

The new results concerning the influence of RPP upon Al doped ZnO films photoluminescence spectra have been obtained: the defects essential reduction (oxygen vacancies, interstitial Zn, aluminium and oxygen atoms); determined the Al and defects energy levels; the increase of the UV PL exciton D0X intensity and the visible PL spectra suppression associated with crystals net defects.

The decrease of surface states density and interface states of the anodic grown and rapid photothermal processed SiO2 films at the pre-oxidation and final steps of the obtaining technology was found and highlighted in the dissertation. The high quality SiO2/Si structures have been obtained by anodic oxidation technology under the UV irradiation and rapid photon annealing (~!~, ~!~, ~!~).

There are presented the investigation results of the gas sensor-structures based on: ZnO:Sn and Cu2O films sensible to low concentrations (1-1.5 ppm) of NO2; ZnO:Al - sensible to relative humidity and smoke; ZnO – to volatile organic compounds (acetone and alcohol); ZnO:Ni to 1000 ppm of NH3 with lower operating temperatures (20-150°C) compare to usual industrial detectors (400-650°C) and minimal reaction time (2-15min). The presented analytical models of the ZnO and Cu2O gas sensors shown the similar to the experimental results; the models could be applied for the technologies and sensors properties optimisation.