Interstitial Doping of SnO₂ Film with Li for Indium-Free Transparent Conductor

SnO 2 films exhibit significant potential as cost-effective and high electron mobility substitutes for In 2 O 3 films. In this study, Li is incorporated into the interstitial site of the SnO 2 lattice resulting in an exceptionally low resistivity of 2.028 × 10 −3 Ω⋅cm along with a high carrier concentration of 1.398 × 10 20 cm −3 and carrier mobility of 22.02 cm 2 /V⋅s. Intriguingly, Li i readily forms in amorphous structures but faces challenges in crystalline formations. Furthermore, it has been experimentally confirmed that Li i acts as a shallow donor in SnO 2 with an ionization energy Δ E D1 of −0.4 eV, indicating spontaneous occurrence of Li i ionization.