ELECTRICAL-PROPERTIES OF PLASMA-GROWN OXIDE ON MBE-GROWN SIGE

The oxidation of semiconductors by RF (radio-frequency) plasma anodiza tion offers several advantages over conventional thermal furnace oxida tion, such as low process temperature and faster oxidation rate. This paper investigates the electrical properties of the plasma-grown oxide on SiGe at room temperature and compares them with thermally grown ox ides of SiGe. An interface state peak has been observed at around E(v) + 0.75 eV. This peak is found to be caused by the presence of the SiG e layer and we present evidence that it is related to a silicon dangli ng bond. We have also observed that the magnitude of the voltage pulse necessary to induce avalanche electron injection increases through th e presence of the SiGe layer. We believe that this is related to the i ncreased ionization rate associated with the smaller bandgap of SiGe. The presence of Ge atoms in the plasma oxide has introduced electron t raps with capture cross sections of the order of 10(-15) and 10(-16) c m(2). Negative bias temperature stress indicates that the bonding betw een Ge and H is weak. This aging test also supports the theory that th e interface states are acceptor-like in the upper half and donor-like in the lower half of the energy bandgap.