Antimony ͑Sb͒, an isoelectronic impurity, has been studied as a surfactant during the lateral epitaxial overgrowth ͑LEO͒ of gallium nitride ͑GaN͒ by metalorganic vapor phase epitaxy ͑MOVPE͒. The presence of Sb in the gas phase was found to alter both the LEO growth rates and the predominant facet formations. Vertical facets to the LEO growth appear with the addition of Sb under conditions that normally produce triangular or sloped sidewalls over a range of growth temperatures. While Sb alters the growth facets, only a small amount of Sb was incorporated into the GaN, suggesting that Sb acts as a surfactant during the GaN MOVPE growth. Sb addition produces surface conditions characteristic of a Ga-rich surface stoichiometry indicating both a possible change in the reactivity of NH 3 and/or enhanced surface diffusion of Ga adatom species. © 2001 American Institute of Physics. ͓DOI: 10.1063/1.1415774͔The use of a suitable impurity, as a surfactant, during the growth of semiconductor films has attracted increasing interest in recent years. [1][2][3][4][5][6] Elemental surfactants are typically characterized by low vapor pressure and low solubility in the solid. They can segregate to the surface and affect surface properties, such as the surface energy, reconstruction and surface kinetic processes of the growing surface. As a result, a small amount of surfactant impurities can significantly alter the growth characteristics and change the resulting film structure without a high level of incorporation into the films. For example, in the case of SiGe growth, antimony ͑Sb͒ has been known to both segregate to the growth front and alter the surface energy of the SiGe. This change in surface energy results in an increase in the epitaxial thickness of the SiGe layer and facilitates layer by layer growth with respect to island growth. 1,2 In this letter, we describe the use of the Sb isoelectronic center as a surfactant during the lateral epitaxial overgrowth ͑LEO͒ of gallium nitride ͑GaN͒ by metalorganic vapor phase epitaxy ͑MOVPE͒.GaN and related materials have been extensively investigated for applications to short wavelength optoelectronics and high temperature and high power electronics. One of the main issues in the GaN crystal growth is the reduction in the threading dislocation density arising from the large lattice mismatch between the GaN film and underlying substrate. The LEO growth technique has been reported as a route for achieving GaN with a significant reduction in the dislocation density. Long-lifetime GaN laser diodes fabricated on LEOgrown materials have been demonstrated. 7 In these applications, it is desirable to increase the yield of the high quality GaN materials in the lateral overgrowth region. A high lateral overgrowth rate, as well as vertical facets, is typically chosen for smooth and rapid coalescence. 8 The growth and structure of LEO GaN materials have been studied through control of many growth parameters, such as the growth temperature, 9 mask orientation, 10,11 V/III ratio, 12 mask fill fact...