Non-polar a-plane and m-plane mixed-polarity gallium nitride (GaN) thin films were deposited on an amorphous glass substrate by conventional RF reactive sputtering, using a high-purity-GaN target and nitrogen (N-2) as a source gas. We observed that decreasing the kinetic and migration energy of the sputtered species by using a low temperature (200 degrees C), N-2-dominant (> 50% of N-2 in an N-2/Ar ambient) condition is essential for obtaining non-polar GaN thin films. This method may be highly advantageous for the development of low-cost non-polar GaN optoelectronic and/or electronic devices.