ANTIMONY SOURCES FOR MOCVD - THE USE OF ET4SB2 AS A P-TYPE DOPANT FORHG1-XCDXTE AND CRYSTAL-STRUCTURE OF THE ADDUCT [ET4SB2.2CDI2]N

Tetraethyldistibine, Et4Sb2, a new antimony source for MOCVD is evalua ted. It is shown to be a useful and safe dopant feedstock for low temp erature growth of p-type Hg1-xCdxTe. Attempted purification of Et4Sb2 by adduct formation with CdI2 resulted in isolation of a polymeric cha in adduct [Et4Sb2 . 2CdI2]n (1). The structure of 1 has been determine d by X-ray crystallography and consists of chains of iodide-bridged Et 4Sb2 . 2CdI2 units which have CdI2 bonded to each antimony atom. Antim ony and two iodine atoms form a trigonal planar arrangement around cad mium, and two weak axial bonds to the iodide atoms of adjacent units g ive distorted trigonal bipyramidal coordination to cadmium. The distib ine 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 ) angstrom. 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.