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We study the low-temperature photoluminescence (PL) of unintentionally doped and Si-doped bulk GaSb grown by low-pressure metal-organic vapour phase epitaxy (MOVPE) from triethylgallium (TEGa), trimethylantimony (TMSb) and silane (SiH 4 ). The background doping with Si in nominally undoped layers is shown to be caused by the TMSb precursor. Intentional Si-doping using silane results in p-doping, a reduction of the material compensation, a substantial decrease in the native acceptor concentration and a dramatic gain in the integral PL intensity compared to unintentionally doped samples. These findings suggest that the Si atoms are incorporated predominantly in the anionic sublattice. The Si-related PL line with a maximum at 0.8 eV observed in the PL spectra of both types of samples at helium temperatures is identified as a transition of a free electron to a neutral acceptor Si Sb with an activation energy of ≈9 meV. The PL spectra of GaSb layers with acceptor concentrations approaching 1 × 10 17 cm −3 , and particularly the 'blueshift' of the peak at 0.800 eV with the temperature rise, can be understood by taking into account the impact of large-scale fluctuations in the charged impurity concentration. The established properties of low-pressure MOVPE-grown Si-doped GaSb are promising for the applicability of this material to GaSb-based devices.

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