Thermal donor formation in direct-plasma hydrogenated n-type Czochralski silicon

The mechanism of a low-temperature doping of silicon initiated by atomic hydrogen is studied. The formation of thermal donors (TDs) in direct-plasma hydrogenated n-type Czochralski silicon upon annealing at 450 °C is investigated by a combination of capacitance–voltage (C–V) and deep level transient spectroscopy (DLTS). The expected hydrogen acceleration of TD formation is retrieved and the same goes for the introduction rate of the oxygen thermal donors (OTDs). It is shown that for short annealing times (30 min), the OTD concentration (NOTD) derived from DLTS is about one decade smaller than the increase in free carrier concentration (Δn), while for a 30 h anneal Δn ≈ NOTD. From this, it is concluded that under the direct-plasma conditions used, other TD formation mechanisms occur simultaneously, involving H as an active participant, in combination with the radiation damage created during the plasma treatment.