Electrical and optical properties of Mn 1.56 Co 0.96 Ni 0.48 O 4 films for infrared detection

Mn 1.56 Co 0.96 Ni 0.48 O 4 films with spinel structure for infrared detection are prepared on Al 2 O 3 substrate by chemical solution deposition method. The resistance vs temperature (R-T) characteristics at 130~304 K temperature range and infrared transmission spectrum (1-10 m) are measured and temperature coefficients of resistance (TCR) are calculated. The conduction process can be explained well by hopping conduction. At low temperature nearest neighbor hopping (NNH) mechanism fits the data well, while at high temperature, variable range hopping (VRH) mechanism dominates the system, and this transition temperature is at about 200 K. The value of TCR is about -3.73% K -1 at 300 K. Mn 1.56 Co 0.96 Ni 0.48 O 4 films exhibit a strong absorption around 2 m which is considered to be corresponding to the gap of energy bands showed by infrared transmission spectrum. The band gap obtained from the transmission spectrum data using the Tauc’s law is ~0.567 eV. Keywords: spinel, Infrared detection, Hopping conduction, Negative temperature coefficients, transition metal oxides.