Enhancing room temperature electron mobility at high carrier concentration in transparent BaSnO3/La:BaSnO3/BaSnO3 heterostructures

Transparent conducting oxides are increasingly important for optoelectronic and thin film transistor applications. La doped BaSnO 3 is a strong candidate for its high transparency, high carrier concentration, high mobility and abundancy. However, due to the lack of lattice-matched substrates, the mobility of La:BaSnO 3 remains inferior to single crystals. Here, by constructing a novel approach via delta doping La:BaSnO 3 in a BaSnO 3 /La:BaSnO 3 /BaSnO 3 (BSO/LBSO/BSO) heterostructure, we achieved room temperature mobility enhancement up to 110 cm 2 ⸱V –1 ⸱s –1 while keeping the high carrier concentration at 5×10 20 cm –3 , reaching to the highest electrical conductivity in BaSnO 3 based systems. The mobility is enhanced more than 100% compared to our La:BaSnO 3 films, which is among the highest mobility in BaSnO 3 based films and heterostructures. From atomic structural investigations, we found that both (1) the carrier confinement due to delta doping and (2) dislocation-free La:BaSnO 3 conducting channel, revealed by atomic resolution scanning transmission electron microscopy (STEM) studies, are responsible for mobility enhancement. The enhanced mobility from heterostructure approach is widely applicable for transparent electrodes and high current thin film transistor applications. • BaSnO 3 and La: BaSnO 3 thickness are optimized via systematic structural and transport properties measurements. • In quantum-confined BSO/LBSO/BSO heterostructures, RT carrier mobility reaches 110 cm 2 ⸱V -1 ⸱s -1 at 5×10 20 cm –3 . • Optical transmission is maintained to 80% in the visible light range in BSO/LBSO/BSO heterostructures. • Atomic scale studies show reduced dislocation density in BSO/LBSO/BSO heterostructures, boosting electron mobility.