TRANSPORT-PROPERTIES OF POLYCRYSTALLINE TIN OXIDE-FILMS

Device quality, tin oxide polycrystalline layers deposited by spray pyrolysis technique have been characterized in terms of morphological, electrical and transport properties. The set of the investigated samples exhibit high values of the mobility (ranging between 30 and 70 cm2 V-1 s-1). The behaviour of the mobility, reported as a function of the carrier concentration and of the size of the crystallites, reveals a transport governed by the processes at the grain boundaries. Furthermore, the behaviour of the mobility with the temperature strongly suggests a transport mechanism determined by tunneling of the potential barrier existing between the grains, and rules out the importance of the thermionic emission process.