Dopant solubility and charge compensation in La-doped SrSnO3 films

Abstract

We investigate lanthanum (La) as an n-type dopant in the strain-stabilized tetragonal phase of SrSnO 3 grown on GdScO 3 (110) using a radical-based hybrid molecular beam epitaxy approach.Fully coherent, epitaxial films with atomically smooth film surface were obtained irrespective of doping density. By combining secondary ion mass spectroscopy and Hall measurements, we demonstrate that each La atom contributes to one electron to the film confirming it occupies Srsite in SrSnO 3 and that it is completely activated. Carrier density exceeding 1 × 10 20 cm -3 was achieved in LSSO films, which is in excellent agreement with the dopant-solubility limit predicted by the density functional theory calculations. A record-high room-temperature mobility of 70 cm 2 V -1 s -1 at 1 × 10 20 cm -3 was obtained in 12 nm La-doped SrSnO 3 film making this the thinnest perovskite oxide semiconductor with a reasonably high electron mobility at room temperature. We discuss the structure-dopant-transport property relationships providing essential knowledge for the design of electronic devices using these materials.

Studies on the structure, optical, ac conduction mechanism by OLPT model and impedance spectroscopy of La-doped Ba2SnO4 Ruddlesden Popper Oxide

“…Ba2SnO4 is made up of a perovskite BaSnO3 and a rock salt layer of BaO, meaning that the number of Ba sites is greater than that of BaSnO3. The solubility limit of La is found to be close to the La-doping in alkaline perovskite oxides [30,31,35]. This indicates that while there are more sites in Ba2SnO4 than in BaSnO3, the La is only occupying the sites that are available in BaSnO3.…”

Separating Electrons and Donors in BaSnO3 via Band Engineering

“…Recently, alkaline earth stannates with perovskite structure have emerged as promising candidates for high RT mobility and high optical transparency. − High RT electron mobility is attributed to the low electron effective mass and weak electron–phonon interaction. , SrSnO 3 (SSO) possesses wider bandgap (4–4.5 eV) and can be doped n -type in thin films with reasonably high electron mobility, 70 cm 2 V −1 s −1 at RT. − Additionally, SSO films can be grown coherently . BaSnO 3 (BSO), on the other hand, possesses a lower bandgap of ∼3 eV, , a relatively larger lattice parameter (4.116 Å), and has not yet been grown fully strained on a commercially available substrate.…”

Wide Bandgap Perovskite Oxides with High Room‐Temperature Electron Mobility

“…102 Perhaps, it is reasonable to say that one of the major breakthroughs in this field came through the first demonstration of a fully coherent film growth of SrSnO 3 . 103 The electrical transport studies have yielded a roomtemperature mobility of 70 cm 2 V -1 s -1 , 104 and there seems much room for improvement through doping optimization and heterostructure engineering such as modulation doping scheme.…”

“…The current record for electron mobility in La-doped SrSnO 3 films on GdScO 3 substrate is 70 cm 2 V -1 s -1 at ~ 1 × 10 20 cm -3 . 104…”

“…Nonetheless, high room-temperature mobility aspect of alkaline-earth stannates has spurred new research avenues including the development of large-lattice parameter substrates, 94 as well as the development of strain-stabilized SrSnO 3 films with reasonably high room-temperature mobility. 103,104 Doped, coherent SrSnO 3 film, in particular, may be more interesting candidate for oxide semiconductor owing to their lower lattice parameter, and ultra-wide bandgap providing opportunities for high power devices. Significant opportunities also exist for heterostructure engineering and for low-dimensional nanostructures and transport.…”