Tunable Transparent Conductors Based on SnO<sub>2</sub>: Theoretical\nand Experimental Studies of Codoping

Transparent\nconducting oxides (TCOs) are widely used in modern\nelectronics because they have both high transmittance and good conductivity,\nwhich is beneficial for many applications such as light-emitting diodes.\nTailoring electronic states and hence the conductive types by design\nis important for developing new materials with optimal properties\nfor TCOs. SnO<sub>2</sub>, with a wide band gap, low cost, no toxins,\nand high stability, is a promising host material for TCOs. Here, we\nperformed a set of hybrid-exchange density functional theory calculations\non the two-element and three-element codoped SnO<sub>2</sub> by using\nSr, Ta, Al, Ga, V, and Nb, which were then validated by the relevant\nexperimental works on SnO<sub>2</sub>. As predicted by the first-principles\ncalculations, the controllability of the electronic states to be n-\nor p-type can be demonstrated experimentally by varying the relative\ndoping concentration between donors (Ta/Nb) and acceptors (Al/Ga).\nOne of the main advantages for these codoping methods is that the\ncharge neutrality problem caused by the dopant can be circumvented.\nThe thin films fabricated showed a low sheet resistance (down to ∼450\nΩ<b>/□</b>) and a high optical transparency (above\n80%). The combination of our calculations and experimental material\nfabrication and characterizations has shown a great potential for\ncodoping SnO<sub>2</sub> for (i) the efficient processing of the integrated\ncircuit composed of both p-type and n-type transistors (using the\nsame target precursors during the deposition) and (ii) a good lattice\nmatching for p–n junctions. Most importantly, our calculations,\nsupported by the experimental works, point to a promising route to\naccelerate the discovery process for the alternative cost-effective\nand high-performance indium-free TCOs using computational material\ndesign.