Photodoping Effect in Manganite Thin Films

Abstract

The Lanthanum Calcium Manganese oxide, La0.67Ca0.33MnO3 (LCMO), belongs to the category of manganite perovskites, which exhibits interesting electronic and magnetic properties such as metal-insulator transition, colossal magnetoresistance (CMR) and multiferroicity. Here, in this study, thin film of thickness 50 nm is deposited on silicon substrate using a DC magnetron sputtering technique. The transition temperature of the film is measured using Physical Property Measurement System and observed to be around 112 K. The LCMO thin film is subjected to light illumination of different wavelengths during electrical characterization. The photoinduced conductivity with a negative Photoresistance (PR) of up to 56 % is observed. The transition temperature remains almost the same during the photodoping effect for different wavelengths than in the dark. Another LCMO thin film with the same divalent Ca doping concentration is fabricated on the silicon substrate with different deposition parameters having a thickness of 22 nm. The transition temperature is found to be around 200 K. On the light illumination, the PR value is – 3.75 %, much less than the previous result. Similar to the previous findings, no significant change in the transition temperature is observed. These results can be explained based on conventional electron-hole pair generation due to light illumination. These outcomes of photodoping effect can have their potential application in optoelectronic devices like optical sensors.