Mg:TiO2 alloy thin films based MOS capacitors grown on GaAs substrates

•Precise and control incorporation of Mg has been done to prepare MgxTi1−xO2 (x = 0.1, 0.2).•Modified Urbach model has been developed to simulate absorption spectrum.•Mg incorporation enhanced the band gap and dielectric constant of the TiO2 TF gradually.•The density of interface states increases due to incorporation of Mg into TiO2 TF.•Enhanced capacitive memory has been recorded for Mg:TiO2 TF devices.