A comparative study of photoconductivity in LaTiO3/SrTiO3 and LaAlO3/SrTiO3 2-DEG heterostructures

Here we compare the growth temperature dependence of the response of LaTiO3/SrTiO3 and LaAlO3/SrTiO3 2D-electron gas (2-DEG) field effect structure to the optical radiation of near ultraviolet frequency and electrostatic gate field. For both the films the resistance of the channel increases significantly as growth temperature is lowered from 800 to 700 degrees C. These heterostructures show the photoconductivity (PC) simulated by UV light of lambda <= 400 nm. The PC follows the stretched exponential dynamics. It is found that photo-response of the LaTiO3 films is prominent and has larger decay time constant as compare to LaAlO3 films. The effect of electric field on the photo-induced conducting state is also studied.