Photoluminescence characteristics of GaN:Si

Both the electrical and optical properties are studied of the GaN:Si films with carrier concentrations ranging from 10^17cm^-3 to 10^19cm^-3.The results indicate that the increase in slope of carrier concentration starts to slow down when the flow rate of SiH_4 is larger than 6.38\mumol/min, which is attributed to the amphoteric character of Si. At the same time, the photoluminescence results show that the FWHM of UV is widened, which can be interpreted quantitatively with a semi-classic model. Furthermore, the intensity ratio between the yellow and the UV luminescences reduces monotonically with Si dopants increasing.