Pulsed laser deposition (PLD) is an efficient technique for fabrication of a variety of thin film materials especially metal oxides. We have developed a compact combinatorial PLD system. The heart of the system is contained in a portable combinatorial thin film deposition flange which can be fitted into any physical vapor deposition system. The eight-inch flange features an automated two-dimensional shutter/mask system and a rotatable substrate heater which can go up to 800 ºC. Spatially selective shadow depositions are carried out by controlling the motion of the shutter/masks which glide over a mounted substrate during and in between depositions. Different designs of discrete combinatorial libraries and continuous composition spreads can be achieved by cutting different apertures on the replaceable masks made of stainless steel sheets. SnO2 based semiconductor gas sensor libraries consisting of 16 discrete compositions have been fabricated, and their operation as electronic noses were successfully tested. By monitoring the number of laser pulses, one can control the deposition of materials at atomic layer level. This layer-by-layer technique can be used for epitaxial growth of continuous composition spreads with controlled compositional variation across chips. Some of the materials we have looked at include ferroelectric BaTiO3-SrTiO3 composition spreads where continuous change in microwave properties were studied and MgO-ZnO composition spreads which can be used for construction of solar blind multi-channel UV detector arrays.