Electrical activation of boron implanted in p-HgCdTe ( x = 0.22) by low-temperature annealing under an anodic oxide

Abstract

The low-temperature electrical activation of boron atoms implanted in p-HgCdTe has been observed for the first time. The bulk crystals of p-Hg 0.75Cd 0.22Te were implanted at room temperature and at 250 °C with 150 keV B + ions up to a dose of 3 × 10 16 cm −2 through an anodic oxide with a thickness of 90 nm. The same control samples were implanted with N + ions under analogous conditions. The two-step post-implant annealing was carried out at 250 °C for 2–4 h and then at 200 °C up to 44 h in a nitrogen atmosphere. Differential Hall effect measurements at 77 K, optical reflection and secondary ion mass spectroscopy were used for implanted surface layer studies. It was established that the doping efficiency of boron atoms amounts of 0.03–14% decreasing with the increasing boron ion dose and becoming higher in the case of ion implantation at 250 °C. Mercury loss was found not to occur from the surface of HgCdTe through an anodic oxide cap during such heat treatment.