Non-polar carbon-doped cubic GaN (c-GaN:C) films were grown by the plasma-assisted molecular beam epitaxy (MBE) using carbon tetra-bromide (CBr4) as a carbon source. The growth was in-situ monitored by the reflection high-energy electron diffraction (RHEED) and for the atomic carbon detection quadrupole mass spectrometry (QMS) was applied. Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) was used to quantify the carbon incorporation behavior. The structural. morphological and optical properties of the epilayers were studied by high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and photoluminescence (PL) measurements at room temperature and at 4K. The electrical properties of c-GaN:C samples were determined by measuring the current-voltage (I-V) characteristics at room temperature. (C) 2008 Elsevier B.V. All rights reserved.