ANNEALING EXPERIMENTS IN HEAVILY ARSENIC-DOPED (HG,CD)TE

Arsenic doped molecular beam epitaxy (MBE) (Hg,Cd)Te films were grown on (Cd,Zn)Te substrates. The concentration of arsenic was varied from 5 x 10(18) cm(3) to 1 x 10(20) cm(-3). After the growth, the epitaxial layers were annealed at various partial pressures of Hg within the ex istence region of(Hg,Cd)Te at temperatures ranging from 400 to 500 deg rees C. Hall effect and resistivity measurements were carried out subs equent to the anneals. 77K hole concentration measurements indicate th at for concentrations of arsenic <10(19) cm(3), most of the arsenic is electrically active acting as accepters interstitially and/or occupyi ng Te lattice sites at the highest Hg pressures. At lower Hg pressures , particularly at annealing temperatures of 450 degrees C and higher, compensation by arsenic centers acting as donors appears to set in and the hole concentration decreases with decrease in Hg pressure. These results indicate the amphoteric behavior of arsenic and its similarity to the behavior of phosphorus in (Hg,Cd)Te previously inferred by us. A qualitative model which requires the presence of arsenic occupying both interstitial and Te lattice sites along with formation of pairs o f arsenic centers is conjectured.