Electrical and optical properties of nanocrystalline yttrium-doped hafnium oxide thin films

Yttrium-doped hafnium oxide (YDH) films have been produced by sputter-deposition by varying the growth temperature (T-s) from room-temperature (RT) to 400 degrees C. The electrical and optical properties of YDH films have been investigated. Structural studies indicate that YDH films grown at T-s = RT-200 degrees C were amorphous and those grown at 300-400 degrees C are nanocrystalline. The crystalline YDH films exhibit the high temperature cubic phase of HfO2. Spectrophotometry analysis indicates that all the YDH films are transparent. The band gap of YDH films was found to be in the range of 6.20-6.28 eV. Frequency variation of frequency dependent resistivity indicates the hopping conduction mechanism operative in YDH films. While the electrical resistivity (rho(ac)) is similar to 1 Omega-m at low frequencies (100 Hz), rho(ac) decreases to similar to 10(-4) Omega-cm at higher frequencies (1 MHz). (C) 2012 Elsevier B.V. All rights reserved.