Effect of oxygen contamination on the properties of the silicon hydrogen alloy materials deposited under conditions near the microcrystalline silicon formation region

Two sets of films of silicon hydrogen alloy (Si:H) were deposited by plasma enhanced chemical vapor deposition (PECVD) method from silane mixed with hydrogen or argon under the deposition conditions suitable for producing micro crystalline silicon ( tc-Si:H) growth. The sets were repeated in two different chambers: one with ultra high vacuum capability having a load lock chamber and the other a single chamber unit without any load lock. The samples deposited in the single chamber unit were found to be contaminated with oxygen. It was observed that the incorporation of unintentional oxygen in the film affects the material properties in a different way for hydrogen or argon dilution. In the case of hydrogen dilution the oxygen contamination results in a shift of the stretching mode frequencies of SiH and SiO bonds and the micro crystalline grain formation is also inhibited by the oxygen impurity, With argon dilution the first effect is present but tc-Si:H growth is not much affected by the oxygen contamination. (C) 2001 Elsevier Science B.V. All rights reserved.