The influence of growth mode on quality of GaN films and blue LED wafers grown by MOCVD

GaN films and multiple quantum well (MQW) LED wafers were grown by a metal-organic chemical vapor deposition (MOCVD) system under low pressure. The growth process was in situ investigated by normal incidence reflectance measurement. The properties of GaN layers were measured by double crystal X-ray diffraction (DCXRD), Hall method and photoluminescence, respectively. The results revealed that not only the properties of GaN layers but also the properties of the blue MQW LED wafers were obviously influenced by the growth mode in the initial stage of high-temperature (HT) GaN growth. The full-width at half-maximum (FWHM) values of the DCXRD peaks, as well as the background carrier concentrations, were obviously decreased when the 3D growth time of HT GaN at the initial stage was prolonged properly. This implies that the dislocation density in GaN films decreased. Moreover, the LED properties, such as the leakage current and the LED output power, would be largely improved if the 3D growth time of HT GaN in the initial stage was proper.