Structural and electrical properties of Iodine doped Hg1−xCdxTe films grown by MBE

Iodine (I) doping in mercury cadmium telluride (Hg_1-xCd_xTe) grown by molecular beam epitaxy (MBE) on CdZnTe substrates with cadmium-iodide (CdI₂) as the dopant source was investigated. I doping concentration in the samples was controlled by CdI₂ source temperature that varied in 110°C-150°C range. Depending upon I doping concentration, the electrical conductivity at 77K for as grown films varied in the 3×10³ Ω^-1m^-1 - 6×10⁴ Ω^-1 m^-1 range and was about of six to ten orders of magnitude higher than those of non-doped HgCdTe films. The Hall coefficient showed classical n-type extrinsic behavior. The electron mobility for lower doping level was observed to be as high as that in an indium-doped material reported in literature [1]. The x-ray diffraction (XRD) studies revealed that there was no prominent change in crystal structure with increasing doping concentration. However, atomic force microscopy (AFM) measurements showed that dislocation densities and consequently defect concentration and size increased with increasing doping concentration.