||Growth temperature dependent critical thickness for phase separation in thick (1 um) InxGa1-xN (x=0.2?0.4)
Yamamoto, A. ,
Hasan, Md Tanvir ,
Kodama, K. ,
Shigekawa, N.Kuzuhara, M.
Journal of Crystal Growth
68 , 2015-06 , ELSEVIER SCIENCE BV
This paper reports phase separation in thick (-1 pm) MOVPE In,Gai_xN (x = 0.2-0.4)films grown by MOVPE at 570-750°C on AIN/Si(111), a-A1203(0001) andGaN/a-A1203(0001) substrates. Phase separation occurs when InGaN thickness exceeds acritical value. Critical thickness for phase separation is markedly increased with decreasinggrowth temperature. It is around 0.2 pm for a film grown at 750°C, while it is more than 1 pmfor that grown at 570°C. No substrate dependencies are found in critical thickness. Thecross-sectional SEM views of phase-separated films grown at 650°C show that phaseseparation is initiated at parts farer more than 0.2 pm from the substrate and extended to thearea near the substrate. SIMS analysis shows a possibility that phase separation is initiatedat a part with relatively large In/Ga ratio fluctuations in InGaN films.