In the present investigation, DLC films were grown by saddle-field fast atom beam (FAB) source using acetylene as source gas. The as-deposited films are having properties like low stress (0.1-0.3 GPa), relatively high hardness (9-21 GPa) values and low amount of unbound hydrogen (0.12-2.9 at.%). Stress per unit hardness (SPUH) has been found to be the ''figure-of-merit'' to describe the film property. A correlation between unbound hydrogen in the DLC films and compressive stress has been established. The effect of nitrogen doping on the properties of DLC films is also investigated. While exploring the conditions for deposition of stress relieved DLC films, many patterns of stress relief behaviour in these films are observed and studied carefully. Surprisingly, we came across new patterns of stress relief behaviour in the case of nitrogen-doped DLC films. This new pattern of the stress relief behaviour, termed as ''hexagonal buckling network'', has been found for the first time and claimed here. The detailed observations of this type of stress relief pattern have been presented.