An Initial Investigation of Nitrogen Doping of Wide-Bandgap HgCdTe During Molecular-Beam Epitaxy Using Ar/N Plasmas

An initial investigation of the use of atomic nitrogen for controlled p-type doping of wide-bandgap Hg 0.3 Cd 0.7 Te (x = 0.7) is reported. Mixtures of argon and nitrogen, ranging in nitrogen concentration from 0.1% to 100%, have been utilized to demonstrate well-controlled nitrogen incorporation in the 10 16 cm -3 to 10 20 cm -3 range using total gas flow rates of 0.3 seem to 4.0 sccm and radiofrequency (RF) powers of 100 W to 400 W. Nitrogen doping exhibits several desirable attributes including abrupt turn-on and turn-off and minimal sensitivity to variations in growth temperature and HgCdTe composition, with no negative effects on HgCdTe dislocation density and morphology. Preliminary electrical measurements indicate primarily n-type behavior in the 10 14 cm -3 to 10 15 cm -3 range in as-grown x = 0.7 HgCdTe and CdTe films doped with nitrogen at 10 18 cm -3 to 10 20 cm -3 concentrations, while ZnTe films have exhibited p-type electrical activity with hole concentrations approaching 10 20 cm -3 .