Investigation on the optical and electrical performance of aluminium doped gallium oxide thin films

Gallium oxide is an extensively researched wide band gap material that has numerous applications in optoelectronic devices. This article focuses on fabrication of amorphous gallium oxide (a-gallium oxide) deposited by RF plasma sputtering at low temperature on glass substrates to fabricate large area flexible electronics. Particularly, this work aims to improve their optical and electrical performances by metal doping as well as substrate preheating. Here, the properties of 9.5% aluminium doped a-Ga2O3 and 6.1% europium doped a-Ga2O3, grown by co-sputtering on soda lime glass substrate at 400 degrees C were analyzed. The thin films produced were nano-structured with an average grain size of similar to 12 nm. The maximum optical transmittance in the UV-vis range for 9.5% Al and 6.1% Eu doped a-Ga2O3 is 82% and 84%, respectively. Although the variations in optical band gap are not appreciable with doping Al and Eu to undoped a-Ga2O3 -3.98 eV, their electronic properties show tremendous difference. Hall effects measurements show that by doping with 9.5% Al, the a-gallium oxide thin films record an increase in both mobility and conductivity of 2 orders. On the other hand, the 6.1% Eu doped a-Ga2O3 does not show any appreciable change in both mobility and conductivity. This was further investigated through first principle density function theory (DFT) to correlate the structure to its properties for both the dopants. Therefore, aluminium doping in a-gallium oxide shows potential towards its application in flexible and cheaper electronic devices.