Effect of heat treatment on nickel manganite thin film thermistors deposited by electron beam evaporation

Thin films of nickel manganite were deposited onto different substrates by means of electron beam evaporation from a powder source of the compound and annealed at 500 and 600 degrees C for 30 min. in air, oxygen or nitrogen t o study the effects of annealing temperature and atmosphere on the structur e and properties of grown thin films. X-ray diffraction and infrared spectr oscopy were used to confirm the formation of nickel manganite; the integrit y of the films and their elemental compositions were assessed using a scann ing electron microscope equipped with an energy dispersive X-ray analyser. Resistance-temperature characteristics were measured between room temperatu re and 600 K. The values of thermistor constant (B) were found to be depend ent on the post growth treatments; annealing in O-2 or air yielded the lowe st values of B similar to 2000-3000 K, while as-deposited and N-2 annealed layers had values of B similar to 5000-6500 K. (C) 1999 Elsevier Science S. A. All rights reserved.