Photoluminescence characterisation of bismuth-doped GaSb

The paper reports on a photoluminescence (PL) characterisation of bismuth-doped gallium antimonide prepared by a travelling heater method (THM) with a Bi-zone. Detailed PL inspection of samples was done, including probing of various surface regions and PL temperature and pump intensity dependencies. In the material grown at 650°C significant shifts of PL peaks and the band-gap narrowing (BGN) were proved by spectral characterisation methods, and caused most likely by tension inside the sample. Material grown at 420°C exhibited very non-uniform luminescent properties. A part of the crystal near the crystal/seed interface showed almost pure excitonic spectra and a strong reduction of the GaSb native acceptor (NA). In regions distant from the interface PL features characteristic for a highly doped and compensated semiconductor were inspected.