Investigations on implantation doping of wide-bandgap II-VI compounds using radioactive dopants

Abstract

Ion implantation of radioactive isotopes of host elements which transmute into relevant acceptors or donors were performed on II-VI compounds. Experiments with PAC measurements, the radio tracer technique and classical electrical methods of semiconductor physics (C-V , Hall effect) were performed to investigate the implantation damage, the diffusion and incorporation of implanted dopants and their doping effects. These measurements revealed that even the incorporation of host elements strongly depends on non-stoichiometry of the well defined preannealed II-VI samples. The dopants Ag, As, Rb and In were incorporated substitutionally via transmutation from host isotopes at lattice sites and act as efficient acceptors and donors respectively.

Acceptor Correlated Centers in II-VI Compounds

“…CdTe, for example, was annealed for 100 h at 750 C. Under Cd pressure we accomplish an n-type carrier concentration of about 10 16 cm À3 , under Te saturated conditions Cd-vacancies were formed yielding a p-type carrier concentration of about 10 16 cm À3 . Before implantation the mechanical polished samples were chemical etched to remove any preparation damage [7].…”

“…After annealing and diffusion the doping layer has a thickness ranging between 300 and 800 nm, while the dopant concentration is about 10 17 cm À3 . The diffusion of implanted isotopes was monitored by g-spectroscopy in combination with the radio tracer method [7]. The doping efficiency was investigated by electrical measurements C ±V, Hall effect and photoluminescence (PL) spectroscopy at 5 K. The rate of isotopes incorporated at lattice site, presenting also a direct measure how largely the radiation damage could be removed by annealing, was elaborated from perturbed angular correlation (PAC) measurements [8].…”