New type of schottky barriers using NiTi shape memory alloy films

With the aim of studying the feasibility of sensors using NiTi shape memory alloy films, we have realised NiTi/Si(n)/Si(n(+)) structures by sputter depositing NiTi contacts on Si substrates. The NiTi sputtering was performed at low substrate temperature (423 K) to avoid the formation of a silicide interfacial layer, Current-voltage (I(V)) measurements on these structures show a rectifying behaviour. The barrier height and ideality factor were determined from these measurements. The influence of the martensitic phase transformation in the NiTi electrode on the electrical properties of the diodes was investigated by recording the I(V) characteristics at various temperatures. This study shows an unusual current decrease with increasing temperature above 353 K. The mechanisms responsible for this phenomenon are discussed.