Growth of metastable InSb1−xBix thin films by multitarget sputtering

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Abstract
Metastable solid‐solution polycrystalline InSb1−xBix films with InBi concentrations up to ∼12 mole% have been grown by multitarget sputtering. This exceeds the solid‐solubility limit of 2.6 mole% InBi reported for melt‐grown bulk InSb1−xBix. The films were deposited on substrates which rotated through separate InSb and Bi discharges maintained at an Ar pressure of 15 mTorr. The relative target voltages were used to control the composition of the deposited films and were chosen such that the deposition rate was always less than a monolayer per target pass. The film growth temperatures investigated were 135 and 165 °C and a (110) preferred orientation was obtained in films grown on Corning 7059 glass substrates. All solid‐solution films were stoichiometric within the accuracy of our electron microprobe, ∼0.5 at.%. The incorporation probability of Bi was found to decrease with increasing Bi impingement flux and with increasing growth temperature. The films were n type with a net room‐temperature carrier concentration increasing monotonically from 1017 to 1018 cm−3 with increasing InBi concentration. Precipitation of metallic Bi was observed in films containing greater than 12 mole% InBi.