Electrical properties of oxygen thermal donors in silicon films synthesized by oxygen implantation

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Abstract
Conductivity and Hall measurements have been carried out on thin silicon films formed by oxygen implantation (SIMOX) and high-temperature annealing. These layers have then been annealed between 450 and 850 °C for 1 h in order to study the electrical behavior of oxygen thermal donors (TD). The maximum donor concentration occurs at 550 °C for TD-I and 750 °C for TD-II. The concentration of TD-II is higher than that of TD-I and the distribution of TD-II can be nonuniform. Thermal ionization energies of these donor states are also derived. A TD level (220 meV) deeper than the typical one (150 meV) is responsible for the electrical properties of the SIMOX layers. Subsequent annealing activates shallow TD states and compensation centers. Thus the ionization energy of the deep TD level decreases greatly, when TDs are generated. High carrier mobilities have been measured which have been limited only at low temperatures by interface scattering.