Thin-Film Gallium Antimonide for Room-Temperature Radiation Detection

Thin-film GaSb diodes were fabricated and investigated for room-temperature radiation detection. GaSb PN junction-based detectors were fabricated by use of both ion-implantation and epitaxial methods, and were compared for crystal quality and detector performance. The implanted junctions were obtained by p-type Be ion-implantation in n-type GaSb substrates whereas the epitaxial junctions were grown by solid-source molecular beam epitaxy. Alpha-particle and fission-fragment peaks were observed in spectra from 241Am and 252Cf. A highly uniform response was obtained from epitaxially grown GaSb junctions whereas large pulse-height response variation was observed for the implanted diodes. The devices were fabricated in the form of metalized squares with dimensions varying from 2 × 2 mm2 to 500 × 500 μm2. Reducing the size reduced detection efficiency but also increased the pulse height response and thus the signal-to-noise ratio, consistent with diode capacitance and output voltage pulse relationships. Cross-sectional transmission electron microscope imaging revealed very high-quality material for the epitaxial structure and implantation-induced damage for the implanted material.