Common origin of doping-limiting mechanisms in IIB-VI compounds and alloys

Wide-band-gap II-VI semiconductors have a potential for a variety of applic ations, which are presently hindered by the difficulties in achieving effic ient doping at both n- and p-side (above 10(18) cm(-3)). The origin and eve n more the microscopic nature of doping problems, remain controversial, In this paper, we have shown that for IIB-VI compounds or alloys the common or igin of very different doping-limiting mechanisms can be traced down to the ratio of covalent radii of the constituent atoms land respective vacancies ). This ratio then determines the ratio of vacancy formation energies, and finally the ratio of their relative concentrations. The practical consequen ce is that the n- and p-type dopability of IIB-VI compounds as well as thei r ternary alloys can be predicted in a simple way. Limits of the approach a re discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.