Cp2mg-Induced Transition Metal Ion Contamination And Performance Loss In Mocvd-Grown Blue Emitting Ingan/Gan Multiple Quantum Wells

The detrimental effects of Cp2Mg-induced trace transition metal (iron and manganese) contamination on the optical performance of metalorganic chemical vapor deposition (MOCVD)-grown blue-emitting InGaN/GaN multiple quantum wells (MQWs) are investigated experimentally. Five samples are grown at various stages of conditioning of a freshly installed MOCVD tool with stainless steel gas lines. Without conditioning, Cp2Mg flow induced Fe and Mn impurities with concentrations of 3 x 10(15) and 3 x 10(14) cm(-3), respectively. These contaminants introduce nonradiative recombination centers with lifetimes on the order of nanoseconds. These impurities also induce indium-clustering related phenomena such as low energy shoulder at low temperature and a strong S-curve shift in emission energy with increasing temperature. Through successive cycles of chamber conditioning, the Fe and Mn concentrations decrease to below their detection limits, and the nonradiative recombination lifetime (+8 ns), internal quantum efficiency (+26%), microphotoluminescence nonuniformity (-4.7%), and S-curve shift (-26 meV) of the MQWs improved. The suppression of the transition metal ion contamination in the MOCVD chamber is shown to be crucial for high performance MQWs and blue light emitting diode growths. Published under license by AIP Publishing.