On the nature of Si-doping in AlGaN alloys

摘要

The silicon doping characteristics of Al_xGa_(1-x)N were investigated over the x = 0.2-0.5 composition range. A combination of Hall effect, thermal admittance and variable temperature photoluminescence spectros-copy indicated that the Si donor level maintained a near effective-mass state behaviour over the composition range studied. Alloy fluctuations appeared to influence the Si donor level, with the activation energies increasing more steeply with increasing compositions than predicted for an effective-mass like donor. Although the Si donor state was localised to some degree within the band gap, the transformation into a DX-centre appeared to be suppressed for these compositions.