99 Effect of Growth Pressure on Indium Incorporation During the Growth of InGaN by MOCVD Journal of ELECTRONIC MATERIALS, Vol. 30, No. 2, 2001 (Received January 24, 2000; accepted October 13, 2000) Regular Issue Paper 99 INTRODUCTION Recent reports of the fabrication of blue and green light emitting diodes (LED) and the demonstration of the room-temperature violet laser emission under continuous wave operations have stimulated a great deal of interest in III-nitride semiconductor materi- als. 1,2 That such light-emitting devices are possible is due to the development of techniques that permit the preparation of high-quality InGaN thin films which contain high levels of In. Even though the growth of InGaN with high In content was possible at a low temperature of around 500°C, the relatively large lattice mismatch with GaN have prevented the growth of high quality InGaN thin films by metalorganic chemical vapor deposition (MOCVD). 3 InGaN thin films, which have good photoluminescence properties have been successfully grown by Yoshimoto et al. by MOCVD with a high ratio of In source flow to a Ga source flow at 800°C. 4 Since then, the attempts to increase the efficiency of In incorporation without structural deterioration of InGaN thin films have been reported by several groups. Such attempts have focused on variations in the growth temperatures, growth rates and V/III ratios during the MOCVD Effect of Growth Pressure on Indium Incorporation During the Growth of InGaN by MOCVD DONG-JOON KIM, 1 YONG-TAE MOON, 1 KEUN-MAN SONG, 1 IN-HWAN LEE, 1 and SEONG-JU PARK 1,2 1.—Kwangju Institute of Science and Technology, Department of Materials Science and Engineering and Center for Optoelectronic Materials Research, Kwangju 500-712, Korea. 2.—e-mail: sjpark@kjist.ac.kr The effect of the growth pressure on the In incorporation in InGaN thin films, grown by metalorganic chemical vapor deposition (MOCVD) have been investi- gated. The InGaN thin films were grown by varying the growth pressures, while maintaining all other growth parameters constant. Photoluminescence and high resolution x-ray diffraction (XRD) measurements showed that the In incorpora- tion in the InGaN thin film was drastically increased with decreasing growth pressures. XRD analysis also revealed that the In concentration in the films was increased by 7.5% as the growth pressure was decreased from 250 torr to 150 torr. This can be attributed to the enhanced mass transportation of precursor gases through the boundary-layer on the substrate in the MOCVD system. Key words: InGaN, metalorganic chemical vapor deposition (MOCVD), x-ray diffraction (XRD), photoluminescence (PL) growth of InGaN thin films. 5–7 However, the effect of growth pressure on In incorporation in the case of MOCVD-grown InGaN films has not been reported, even though it plays a critical role in the growth of InGaN thin films. This study provides evidence to show that the growth pressure plays an important role in the incorporation of In in InGaN thin films grown by MOCVD. The In composition of the InGaN was estimated by x-ray diffraction analysis. The opti- cal and structural qualities of InGaN thin films were evaluated by measuring the room-temperature pho- toluminescence (PL) and x-ray θ-rocking curve for InGaN (002) and (102) planes. EXPERIMENTAL All epitaxial thin films were grown on (0001) sap- phire substrates in an MOCVD reactor by using trimethylgallium (TMGa), trimethylindium (TMIn), and ammonia. Prior to the deposition of the GaN nucleation layer, the sapphire substrates were ex- posed to H 2 at 1030–1040°C for 10 min. A 1-μm-thick GaN buffer layer was deposited at 1020°C after coat- ing GaN nucleation layers on top of the sapphire substrates to thickness of 30 nm at 505°C. Two series InGaN thin films, approximately 0.1-μm in thickness, were grown on top of the GaN buffer layers. The first series of InGaN thin films were grown at 780°C under