We demonstrate here a simple and effective (n,m)-selective growth of single-walled carbon nanotubes (SWCNTs) in an aerosol floating catalyst chemical vapor deposition (CVD) process by introducing a certain amount of ammonia (NH3). Chiralities of carbon nanotubes produced in the presence of 500 ppm NH3 at 880 degrees C are narrowly distributed around the major semiconducting (13,12) nanotube with over 90% of SWCNTs having large chiral angles in the range 20 degrees-30 degrees, and nearly 50% in the range 27 degrees-29 degrees. The developed synthesis process enables chiral-selective growth at high temperature for structurally stable carbon nanotubes with large diameters.