Antimony sources for MOCVD. The use of Et₄Sb₂ as a p-type dopant for Hg_1-xCd_xTe and crystal structure of the adduct [Et₄Sb₂ · 2CdI₂]_n

Tetraethyldistibine, Et₄Sb₂, a new antimony source for MOCVD is evaluated. It is shown to be a useful and safe dopant feedstock for low temperature growth of p-type Hg_1-xCd_xTe. Attempted purification of Et₄Sb₂ by adduct formation with CdI₂ resulted in isolation of a polymeric chain adduct [Et₄Sb₂ · 2CdI₂]_n (1). The structure of 1 has been determined by X-ray crystallography and consists of chains of iodide-bridged Et₄Sb₂ · 2CdI₂ units which have CdI₂ bonded to each antimony atom. Antimony and two iodine atoms form a trigonal planar arrangement around cadmium, and two weak axial bonds to the iodine atoms of adjacent units give distorted trigonal bipyramidal coordination to cadmium. The distibine molecules display a skew configuration of the ethyl substituents. The Sb^II-Sb^II and Sb^II-Cd^II distances are 2.784(2) and 2.822(2) Å respectively. Dropwise addition of Me₂Cd to Et₄Sb₂ in the absence of solvent gave an insoluble 1:1 adduct. Et₄Sb₂ reacts with Te but not with Cd or Hg.