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 (Ts) from room-temperature (RT) to 400 °C. The electrical and optical properties of YDH films have been investigated. Structural studies indicate that YDH films grown at Ts = RT − 200 °C were amorphous and those grown at 300–400 °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 (ρac) is ~ 1 Ω-m at low frequencies (100 Hz), ρac decreases to ~ 10− 4 Ω-cm at higher frequencies (1 MHz).

► Yttrium doped hafnia (YDH) thin films were fabricated using sputter-deposition. ► The effect of growth temperature on the microstructure of YDH films is significant. ► A temperature of 300 °C results in the formation of cubic YDH films. ► The band gap of YDH films is in the range of 6.20–6.28 eV.