EFFECTS OF SUBSTRATE-TEMPERATURE ON THE STRUCTURE AND PROPERTIES OF REACTIVE PULSED-LASER DEPOSITED CNX FILMS

The effects of substrate temperature (25 less than or equal to T-s les s than or equal to 437 degrees C) on the structure and properties of r eactive pulsed laser deposited (RPLD) carbon nitride (CNx) films prepa red at a fixed nitrogen ambient pressure of 200 mTorr were investigate d. The structure and composition of the films were characterized by X- ray diffraction, X-ray photoelectron spectroscopy and IR absorption, w hile the electrical and optical properties were studied by phototherma l deflection spectroscopy, optical transmission and electrical conduct ivity measurements. The results show that the films contain graphitic rings, in which some of the carbon atoms are replaced by nitrogen atom s. The atomic fraction of nitrogen drops from 0.27 to 0.13 as T-s incr eases from 25 to 437 degrees C, indicating that the incorporation of n itrogen is hindered by a rise in T-s. As a consequence, the optical ba nd gap and the width of electron tail states become narrower, and the room temperature electrical conductivity increases greatly such that t he properties of the films deposited at high temperature approach thos e of graphite.