Deposition of (Bi,Sb)2Te3 films by magnetron co-sputtering from two targets-first results

Sputtered (Bi,Sb)/sub 2/Te/sub 3/ films show an excellent adhesivity on Kapton substrates and are suitable for patterning by wet etching. The known problem of strong deviation from stoichiometry in these films results from both the different sticking coefficients and the resputtering of the elements during the film growth. An oversupply of tellurium atoms is a possible and usually applied solution. A coating system was used which enables the control of direction and intensity of the particle flux from two magnetron sources separately. The targets consist of (i) stoichiometric (Bi/sub 0.25/Sb/sub 0.75/)/sub 2/Te/sub 3/ and (ii) pure tellurium. The experimental arrangement allows one to control the Te:(Bi,Sb) flux ratio R/sub F/ in a wide range. WDX analysis of the composition shows, that the films are nearly stoichiometric in the range 1.7/spl les/R/sub f//spl les/4 at substrate temperature T/sub S/=300/spl deg/C. A small deviation from stoichiometry was observed depending on the variation of T/sub S/.