Bismuth-assisted low-temperature growth of flexible GaSb thin films by multi-cathode RF magnetron sputtering

GaSb-based thin films are expected to be applicable to biomedical and environmental devices requiring efficient operation in the near-infrared region. In this study, the effects of dilute Bi doping on the structural properties and chemical stability of GaSb thin films were examined. GaSb and GaSb 1− x Bi x ( x = 0.011, 0.013, or 0.032) thin films were grown at 320 °C on quartz substrates and PI films by multi-cathode RF magnetron sputtering. The crystallinity of the GaSb/quartz was superior to that of the GaSb/PI. Bi doping improved the crystallinity of the GaSb thin films with the exception of GaSb 0.968 Bi 0.032 /quartz, for which the crystallinity deteriorated owing to abnormal growth due to Bi cluster formation. In addition, the crystallinity of GaSb 1− x Bi x /PI was drastically improved at x = 0.032. The increases in grain size and hole concentration caused by Bi doping indicate that Bi assists the growth of GaSb thin films. Furthermore, elution tests revealed that Bi doping suppresses the elution of highly toxic Sb under simulated physiological conditions. These findings have the possibility to hasten the development of flexible GaSb-based biomedical and environmental devices with improved safety and lower environmental burden.