GaN-InGaN quantum well and LED structures grown in a close coupled showerhead (CCS) MOCVD reactor

A Close Coupled Showerhead MOCVD reactor has been used to grow GaN-InGaN quantum well (QW) structures and LEDs using two different growth regimes, one in which the wells are grown at a lower temperature than the barriers and the other in which both are grown at the same temperature. In general the optical quality of single temperature multi-quantum wells (MQWs) are superior to that of structures grown at two temperatures but the latter have been proved easier to optimise for operation at longer wavelengths. Improved emission wavelength uniformity has been noted for the single temperature structures and XRD and low temperature PL measurements of the latter have indicated that high quality structures have been achieved. Time resolved PL has shown that the radiative carrier lifetime increases with the indium content of the quantum wells making longer wavelength structures more susceptible to competition from non-radiative recombination.