MOLECULAR-BEAM EPITAXY OF IODINE-DOPED CDTE AND (CDMG)TE

The n-type doping of CdTe and (CdMg)Te by the use of the solid dopant source material ZnI2 is reported. Doping levels as high as 7 x 10(18) cm-3 have been obtained in CdTe with carrier mobilities around 500 cm2/V.s at room temperature. For a dopant incorporation higher than 1 x 10(19) cm-3 the free carrier concentration decreases, indicating the onset of a compensation mechanism, which is observed in the case of chlorine and bromine doping, too. Preliminary experiments show that with increasing Mg concentration the free carrier concentration decreases. Nevertheless, CdMgTe with a magnesium concentration x = 0.37 (band gap 2.2 eV at room temperature) can be doped up to 2 x 10(17) cm-3. The existence of deep donor levels in this CdTe based ternary is not supposed to be the only reason for the reduction of the free carrier concentration. For high Mg support during molecular beam epitaxial (MBE) growth of wide gap (CdMg)Te layers, the ZnI2 incorporation is reduced, leading to low doping levels, too.