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The emphasis is on the study of the relationship between oxygen profiles, crystallographic structure and electrical and physical properties of the YBaCuO thin films formed in situ at the same and optimized conditions of sample deposition for the microwave applications and further submitted to the different conditions of sample cooling. Particularly interesting results are obtained by sample cooling at low oxygen pressure in the presence of oxygen plasma. The studies of the oxygen depth concentration profiles and of the oxygen contents are carried out using the Nuclear Reaction Analysis (NRA). These results are correlated, on one hand, with the measurements of the atomic composition and structure by RBS, XRD and TEM and, on the other hand, by the measurements of the electrical and physical properties Tc, Jc and microwave surface resistance Rs. All results are consistent with the idea that the fully oxygenated films are formed during in situ growth at T approximately 700 degrees Celsius. During the sample cooling the oxygen loss or uptake take place as a function of oxygen chemical potential. A huge oxygen overdoping is evidenced in the samples cooling down in the presence of the oxygen plasma. Moreover, the presence of 'easy paths' for oxygen diffusion in c-axis oriented thin films is evidenced. Their oxidation state strongly affects Jc and Rs properties in opposite to Tc one and is sensitive to the room temperature corrosion. The fundamental and applied consequences of these findings for the mechanism of thin film growth and for the properties of the films in the presence of cathodic plasma or laser plume are analyzed.
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