We report on a single domain growth of InN on sapphire substrates by electric-field enhanced polarity-controlling metal-organic chemical vapor deposition. When the electric field is applied in the opposite direction to the film growth, InN grows inverted hexagonal-pyramid shapes with Inpolarity surfaces. A growth model is presented to explain the rapid growth of the single domain InN with In-polarity under electric field using the knowledge of the domain wall structure and the growth of ferroelectrics in the external field. © 2013 The Japan Society of Applied Physics.