AVS 50th International Symposium
    Semiconductors Tuesday Sessions
       Session SC-TuM

Invited Paper SC-TuM8
Growth of InN and Related Compounds by RF Plasma Molecular Beam Epitaxy

Tuesday, November 4, 2003, 10:40 am, Room 321/322

Session: Narrow Gap Semiconductors
Presenter: W.J. Schaff, Cornell University
Authors: W.J. Schaff, Cornell University
H. Lu, Cornell University
Correspondent: Click to Email
InN is of interest for small bandgap, low effective mass applications. InN is grown with a remote RF plasma source of nitrogen using molecular beam epitaxy at substrate temperatures near 500C. GaN or AlN buffers on c-plane sapphire substrates are required for best InN quality. More than 200 wafers have been grown. All exhibit a direct bandgap near 0.7eV which is frequently measured for MBE grown InN@footnote 1@ and agrees with theoretical calculations.@footnote 2@ Bandfilling effects explain observations of increased energy of optical transitions at increased electron density.@footnote 3@ Control of electrical conductivity is limited. Undoped InN is n-type with electron densities that are usually high enough to be degenerate. Electron density falls with InN layer thickness and can be as low as 3E17cm-3 in layers beyond 5 microns thick. 300K mobility is beyond 1000 cm2/Vsec in 1 micron layers and is above 2000 in 5-7 micron thick layers.@footnote 4@ Dislocation density also decreases with InN layer thickness. A cause-effect relationship between electron and dislocation density is not established yet. Si is introduced as a shallow donor while unintentional shallow donors have not been identified. InN has not been made p-type. Mg and Be doping affects electron density and mobility, but net p-type conductivity has not been seen. InN can be grown in the a-plane direction when a-plane GaN or AlN buffers are used on r-plane sapphire.@footnote 5@ In contrast, direct growth on r-plane sapphire without a buffer layer creates predominantly a cubic form of InN.@footnote 6@ Mobility is lower and carrier density is higher in InN in the forms which are not c-plane wurtzite. @FootnoteText@ @footnote 1@V. Yu. Davydov, A. A. Klochikhin, R. P. Seisyan, et al, phys. stat. Sol. (b), 229, R1 (2002).@footnote 2@ F. Bechstedt, J. Furthmüller, M. Ferhat, L. K. Teles, L. M. R. Scolfaro, J. R. Leite, V. Yu. Davydov, O. Ambacher, and R. Goldhahn, phys. stat. sol. a 195, 628 (2003).@footnote 3@ V. Cimalla, Ch. Förster, G. Kittler, I. Popa, R. Kosiba, G. Ecke, O. Ambacher,R. Goldhahn, S. Shokhovets, A. Georgakilas, H. Lu, W. Schaff, Proc. ICNS-5 submitted to phys. stat. sol (a) 195, No. 1, 3-10 (2003).@footnote 4@ H. Lu, W.J. Schaff, L.F. Eastman, GaN and Related Alloys - 2001. Symposium (Materials Research Society Symposium Proceedings Vol.693) Mater. Res. Soc, 2002, xv+860 p. (9-14).@footnote 5@ H Lu, W.J. Schaff L F. Eastman, J. Wu, Wladek Walukiewicz, Volker Cimalla, Oliver Ambacher, submitted to Applied Physics Letters.@footnote 6@ V. Cimalla, J. Pezoldt, O. Ambacher, L. Spiess, and G. Teichert, H. Lu and W. J. Schaff, submitted for publication.