Transparent Ta doped SnO2 films deposited by RF co-sputtering

Tantalum doped tin oxide (TaTO) has the potential to surpass the more commonly used transparent electrode, fluorine doped tin oxide (FTO), in terms of electrical conductivity as it avoids the self-compensating F interstitial defects that limit FTO. However, high mobility TaTO has only been deposited by pulsed laser deposition (PLD), a slow, expensive and non-scalable technique. In this work, TaTO was deposited by RF co-sputtering of SnO
₂
and Ta
₂
O
₅
. A range of sputtering parameters were investigated varying the tantalum content and substrate temperature. Resistivities of 8.5×10
^-3
Ωcm were achieved under the best conditions, corresponding to a carrier concentration of 4.4 × 10
¹⁹
cm
^-3
and Hall mobility of 16.6 cm
²
V
^-1
s
^-1
along with transmission of >75% across the visible and near infrared was achieved. X-ray diffraction patterns informed that the limitation of the co-sputtering deposition method arose from uneven distribution of dopant throughout the films.