Indium incorporation into InGaN and InAlN layers grown by metalorganic vapor phase epitaxy M. Leszczynski a,b,n,1,2 , R. Czernecki a,b , S. Krukowski a , M. Krysko a , G. Targowski b , P. Prystawko a,b , J. Plesiewicz b , P. Perlin a,b , T. Suski a a Institute of High Pressure Physics UNIPRESS, Warsaw, Poland b TopGaN, Warsaw, Poland article info Available online 12 November 2010 Keywords: A1. Growth models A3. Metalorganic vapor phase epitaxy B1. Nitrides B2. Semiconductor ternary compounds abstract Experimental data on indium incorporation in InGaN and InAlN layers grown by metalorganic chemical vapor epitaxy (MOVPE) on bulk GaN substrates are presented and discussed. For the step-flow growth mode, realized for InGaN layers grown at relatively high temperatures (around 800 1C), incorporation of indium increases with growth rate, and similarly, with a decrease in GaN substrate misorientation. Both dependences are explained by a higher velocity of flowing steps incorporating the indium atoms. For InAlN layers, three-dimensional nucleation takes place, and thus no significant changes of indium incorporation versus either growth rate or GaN substrate misorientation were observed. & 2010 Elsevier B.V. All rights reserved. 1. Introduction InGaN and InAlN are used in UV/violet/blue/green light emitting diodes (LEDs), laser diodes (LDs), as well as other optoelectronic devices, as detectors or sensors. Despite big commercial success of nitride semiconductors in multibillion markets of solid state lighting, illumination, data storage and laser projection, the technology of (InGaAl)N is still far from being mature. For example, the wall plug-efficiencies of the commercial violet LDs (405 nm) are only about 20% [1]—twice less than in the case of red and infrared GaAs-based LDs. For longer wavelengths, these efficiencies are even lower (around 2% for green 500 nm emitters [2]), which is related to difficulties in growing InGaN layers (active region of the emitters) with high In content. These difficulties stems from three main issues: (i) Low growth temperature, which slows down surface diffusion of in-coming atoms and thus stimulates three-dimensional growth. Moreover, at low temperature, incorporation of oxy- gen (always present even in the ppb-purified gases) becomes higher, resulting in dislocation decoration and formation of pin-holes. (ii) Large lattice mismatch between InN and GaN (10%) leading to indium segregation, titling of the layer planes with respect to the misoriented substrate [3] and defect (dislocations, cracks, pin-holes, etc.) formation [4]. (iii) Built-in electric fields in the wurtzite structure along c-direction, which spatially separate electrons and holes, decreasing the emitter efficiency [5]. InGaN layers are used not only as quantum wells emitting light, but also as quantum barriers, waveguides and subcontact layers. The relation of their structural and morphological properties with growth parameters in metalorganic vapor phase epitaxy (MOVPE) was discussed in a number of papers (for example, in Refs. [6–9]). Growth of InAlN layers has not been examined so often, as only recently these layers have found applications in electronic and optoelectronic devices [10,11]. A significant advantage of these layers is the possibility of having them lattice matched (for indium content of about 17%) to GaN. Their disadvantage is the very difficult growth related to AlN–InN lattice mismatch (12.5%), i.e. even higher than that of InN–GaN, increased oxygen incorporation due to aluminum presence and smaller aluminum surface diffu- sivity in comparison to gallium. The paper is devoted to comparison of InGaN and InAlN layers grown by MOVPE in the same conditions and critical assessment of these differences. First, we will show a difference in indium incorporation versus growth rate, then a dependence of indium incorporation on GaN substrate misorientation will be shown and discussed, and finally, a difference in layer morphology will be used to explain qualitatively all the experimental data. In particular, we draw attention of the reader to the second part on GaN substrate misorientation. The application of such misoriented Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jcrysgro Journal of Crystal Growth 0022-0248/$ - see front matter & 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jcrysgro.2010.10.050 n Corresponding author at: Institute of High Pressure Physics UNIPRESS, 01 142Warsaw, Poland. Tel.: + 48 602391349. E-mail address: mike@unipress.waw.pl (M. Leszczynski). 1 www.unipress.waw.pl 2 www.topgan.fr.pl Journal of Crystal Growth 318 (2011) 496–499