Abstract
•We examined the Bi doping effect on GaN layers properties, grown by LT-MOVPE.•No obvious dependence of growth rate with TMBi flow rate.•TMBi flow rate addition resulted in a reduction of reflectivity oscillation mean value.•We note the appearance of islands and columns containing Bi on layers surface.•While there is a decrease in surface roughness suggesting Bi surfactant effect.
Undoped GaN and diluted GaNBi alloys were grown on (0001) sapphire substrate by metal–organic vapor phase epitaxy (MOVPE) at 480°C. By using in-situ laser reflectometry, it is found that the increase of TMBi flow rate leads to a reduction of the average value of reflectivity oscillations. Scanning electron microscopy (SEM) images gave a clear observation of the TMBi increasing amount effect on the surface morphology. The appearance of different structure (islands and columns) on GaN surface could be responsible to the reduction of the reflectivity oscillations average value. The energy dispersive X-ray (EDX) analysis showed that the observed structures were only composed of Bi compared to the flat GaN surface. Moreover, the surface morphology between islands and columns is improved when we increase the TMBi flow rate. This improvement is consistent with the decrease of root mean square (RMS) roughness, as measured by atomic force microscopy (AFM).