Interstitial doping of SnO₂ film with Li for indium-free transparent conductor

Abstract The SnO2 film exhibits significant potential as a cost-effective and high electron mobility substitute for In2O3 films. In this study, Li is incorporated into the interstitial site of the SnO2 lattice resulting in an exceptionally low resistivity of 2.028 × 10-3 Ω·cm along with a high carrier concentration of 1.398 × 1020 cm-3 and carrier mobility of 22.02 cm2/V·s. Intriguingly, Lii readily forms in amorphous structures but faces challenges in crystalline formations. Furthermore, it has been experimentally confirmed that Lii acts as a shallow donor in SnO2 with an ionization energy ΔED1 of -0.4 eV, indicating spontaneous occurrence of Lii ionization.