Physical properties of silicon doped hetero-epitaxial MOCVD grown GaN: influence of doping level and stress

摘要

Silicon doped layers GaN were grown with MOCVD on sapphire substrates using silane as silicon precursor. The influence of the silicon doping concentration on the physical and optical properties is investigated. A linear relationship is found between the silane-input molfraction and the free carrier concentration in the GaN layers. The morphology of the samples is drastically changed at high silicon concentrations. Photoluminescence was used to probe bandgap variations as function of the silicon concentration. Increasing of the doping concentration led to a continuous shift of the exciton related PU to lower energies, while the intensity of the UV emission was found to increase up to a carrier concentration of n=2.5×10{sup}18cm{sup}(-3)