We report results of a photoluminescence (PL) study of homoepitaxial N-polar GaN films grown by metal-organic chemical vapour deposition on vicinal (0 0 0 (1) over bar) GaN single crystal substrates. Off-angles of 2 degrees and 4 degrees towards the [1 1 (2) over bar 0] direction as well as 4 degrees in the [1 0 (1) over bar0] direction were investigated. Along with a remarkable improvement of the epilayer morphology, a significant reduction of the unintentional/intrinsic donor concentration is achieved for all considered misorientations. As a consequence, PL spectra with narrow bound and free excitonic lines were observed. The misorientation of 4 towards the [1 1 2 0] direction results in an N-polar epilayer of the best optical quality.