‘Semi-insulating’ silicon using deep level impurity doping: problems and potential

Abstract

The possibility of using deep level impurities to obtain ‘semi-insulating’ Czochralski silicon of near-intrinsic resistivity for microwave applications has been analysed. It is shown that co-doping with a deep donor and deep acceptor is effective in producing high resistivity p-type silicon if a single sufficiently deep donor is not available. Values of deep impurity levels and their concentrations ideally suited for the purpose have been evaluated. It is found that there is a trade-off between control over deep impurity doping concentration and the maximum achievable resistivity. Calculations of resistivity using published data for a number of transition metal impurities such as Au, Ag, Cr, Co, Pd, Pt, V and Mn show that V and Mn are best suited to achieve the goal if Au and Ag are disqualified due to high diffusivity. A comparison of Si:Mn with semi-insulating GaAs:Cr shows the limitations of the effectiveness of deep level doping in silicon.