The deposition of a-Si:H at high temperature using the dc-magnetron assisted silane decomposition (MASD) technique was optimized. MASD was found to have particular advantages over other high-temperature deposition techniques. In particular this technique allows the deposition of high quality films at a high deposition rate. The modelling of the plasma deposition and film growth proved that the SiH3 - flux is the most important parameter. The films also show metastability under illumination though less pronounced than in case of those which were prepared by normal PECVD in the triode reactor. The MASD technique in addition allows the incorporation of rare earth ions (Er, Yb) which opens a new field of research and application. A light-emitting diode was realized with room-temperature emission at 1.537µm. The research concentrated however on the more fundamental questions such as the excitation mechanism of the Er-ions.
The influence of ion-bombardment during film growth was studied. The connection between electronic properties and internal plasma parameters was established. Ion distribution functions, maximal energy and the ion flux on the substrate were measured in hydrogen, argon and silane plasmas pin and nip structures were prepared and particular emphasis was given to the examination of the influence of ion bombardment during the deposition of the front layer. It was shown that ion bombardment has a significant influence on the top-interface recombination. Considerable improvement was achieved by using hydrogen bombardment prior to the deposition of the top layer. A remarkable result was that the ion bombardment also influences the stability of the device.
The methods for the measurement of internal plasma parameters were developed. Measurements have been carried out in collaboration with the IP-2 team on silane, hydrogen and argon plasmas. In collaboration with the team IP-1 a model for the silane plasma was developed which allows the theoretical simulation. The most important result was that a quantitative description can be obtained if one assumes that the relevant species for film growth is the SiH3-radical.
The work concentrated on the study of the kinetics and the mechanism of light degradation in a-Si:H. Samples were studied from IP-1, IP-2 and UM. It turned out that the degradation mechanism is particularly interesting in doped and compensated films where an additional mechanism of defect creation may be important.