skip to main content

Title: Combined experimental-theoretical study of electron mobility-limiting mechanisms in SrSnO3

The discovery and development of ultra-wide bandgap (UWBG) semiconductors is crucial to accelerate the adoption of renewable power sources. This necessitates an UWBG semiconductor that exhibits robust doping with high carrier mobility over a wide range of carrier concentrations. Here we demonstrate that epitaxial thin films of the perovskite oxide NdxSr1xSnO3(SSO) do exactly this. Nd is used as a donor to successfully modulate the carrier concentration over nearly two orders of magnitude, from 3.7 × 1018 cm−3to 2.0 × 1020 cm−3. Despite being grown on lattice-mismatched substrates and thus having relatively high structural disorder, SSO films exhibited the highest room-temperature mobility, ~70 cm2 V−1 s−1, among all known UWBG semiconductors in the range of carrier concentrations studied. The phonon-limited mobility is calculated from first principles and supplemented with a model to treat ionized impurity and Kondo scattering. This produces excellent agreement with experiment over a wide range of temperatures and carrier concentrations, and predicts the room-temperature phonon-limited mobility to be 76–99 cm2 V−1 s−1depending on carrier concentration. This work establishes a perovskite oxide as an emerging UWBG semiconductor candidate with potential for applications in power electronics.

; ; ; ; ; ; ;
Award ID(s):
2011401 1741801
Publication Date:
Journal Name:
Communications Physics
Nature Publishing Group
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Room temperature semiconductor detector (RTSD) materials for γ‐ray and X‐ray radiation are in great demand for the nonproliferation of nuclear materials as well as for biomedical imaging applications. Halide perovskites have attracted great attention as emerging and promising RTSD materials. In this contribution, the material synthesis, purification, crystal growth, crystal structure, photoluminescence properties, ionizing radiation detection performance, and electronic structure of the inorganic halide perovskitoid compound TlPbI3are reported on. This compound crystallizes in the ABX3non‐perovskite crystal structure with a high density ofd = 6.488 g·cm–3, has a wide bandgap of 2.25 eV, and melts congruently at a low temperature of 360 °C without phase transitions, which allows for facile growth of high quality crystals with few thermally‐activated defects. High‐quality TlPbI3single crystals of centimeter‐size are grown using the vertical Bridgman method using purified raw materials. A high electrical resistivity of ≈1012 Ω·cm is readily obtainable, and detectors made of TlPbI3single crystals are highly photoresponsive to Ag KαX‐rays (22.4 keV), and detects 122 keV γ‐rays from57Co radiation source. The electron mobility‐lifetime productµeτewas estimated at 1.8 × 10–5cm2·V–1. A high relative static dielectric constant of 35.0 indicates strong capability in screening carrier scattering and charged defects in TlPbI3.

  2. Abstract

    The transfer‐free direct growth of high‐performance materials and devices can enable transformative new technologies. Here, room‐temperature field‐effect hole mobilities as high as 707 cm2V−1s−1are reported, achieved using transfer‐free, low‐temperature (≤120 °C) direct growth of helical tellurium (Te) nanostructure devices on SiO2/Si. The Te nanostructures exhibit significantly higher device performance than other low‐temperature grown semiconductors, and it is demonstrated that through careful control of the growth process, high‐performance Te can be grown on other technologically relevant substrates including flexible plastics like polyethylene terephthalate and graphene in addition to amorphous oxides like SiO2/Si and HfO2. The morphology of the Te films can be tailored by the growth temperature, and different carrier scattering mechanisms are identified for films with different morphologies. The transfer‐free direct growth of high‐mobility Te devices can enable major technological breakthroughs, as the low‐temperature growth and fabrication is compatible with the severe thermal budget constraints of emerging applications. For example, vertical integration of novel devices atop a silicon complementary metal oxide semiconductor platform (thermal budget <450 °C) has been theoretically shown to provide a 10× systems level performance improvement, while flexible and wearable electronics (thermal budget <200 °C) can revolutionize defense and medical applications.

  3. We report the use of suboxide molecular-beam epitaxy ( S-MBE) to grow β-Ga 2 O 3 at a growth rate of ∼1 µm/h with control of the silicon doping concentration from 5 × 10 16 to 10 19  cm −3 . In S-MBE, pre-oxidized gallium in the form of a molecular beam that is 99.98% Ga 2 O, i.e., gallium suboxide, is supplied. Directly supplying Ga 2 O to the growth surface bypasses the rate-limiting first step of the two-step reaction mechanism involved in the growth of β-Ga 2 O 3 by conventional MBE. As a result, a growth rate of ∼1 µm/h is readily achieved at a relatively low growth temperature ( T sub ≈ 525 °C), resulting in films with high structural perfection and smooth surfaces (rms roughness of <2 nm on ∼1 µm thick films). Silicon-containing oxide sources (SiO and SiO 2 ) producing an SiO suboxide molecular beam are used to dope the β-Ga 2 O 3 layers. Temperature-dependent Hall effect measurements on a 1 µm thick film with a mobile carrier concentration of 2.7 × 10 17  cm −3 reveal a room-temperature mobility of 124 cm 2  V −1  s −1 that increases to 627 cm 2  V −1more » s −1 at 76 K; the silicon dopants are found to exhibit an activation energy of 27 meV. We also demonstrate working metal–semiconductor field-effect transistors made from these silicon-doped β-Ga 2 O 3 films grown by S-MBE at growth rates of ∼1 µm/h.« less
  4. Abstract

    The development of in situ growth methods for the fabrication of high‐quality perovskite single‐crystal thin films (SCTFs) directly on hole‐transport layers (HTLs) to boost the performance of optoelectronic devices is critically important. However, the fabrication of large‐area high‐quality SCTFs with thin thickness still remains a significant challenge due to the elusive growth mechanism of this process. In this work, the influence of three key factors on in situ growth of high‐quality large‐size MAPbBr3SCTFs on HTLs is investigated. An optimal “sweet spot” is determined: low interface energy between the precursor solution and substrate, a slow heating rate, and a moderate precursor solution concentration. As a result, the as‐obtained perovskite SCTFs with a thickness of 540 nm achieve a record area to thickness ratio of 1.94 × 104 mm, a record X‐ray diffraction peak full width at half maximum of 0.017°, and an ultralong carrier lifetime of 1552 ns. These characteristics enable the as‐obtained perovskite SCTFs to exhibit a record carrier mobility of 141 cm2V−1s−1and good long‐term structural stability over 360 days.

  5. Abstract

    Perovskite oxides are ABO3‐type compounds with a crystal structure capable of accommodating a large number of elements at A‐ and B‐sites. Owing to their flexible structure and complex chemistry, they exhibit a wide range of functionalities as well as novel ground states at the interface. However, in comparison with conventional semiconductors such as silicon, they possess orders of magnitude lower room‐temperature electron mobilities limiting their room‐temperature electronic applications. For example, in a prototypical doped SrTiO3, the room‐temperature electron mobility remains below 10 cm2V−1s−1regardless of the defect minimization. Discovery of high room‐temperature mobility in alkaline‐earth stannates such as BaSnO3and SrSnO3constitutes a significant advancement toward all‐perovskite electronic and spintronic devices. Alkaline‐earth stannates also possess wide‐to‐ultra wide bandgaps that make them potentially suitable candidate for transparent conductors, power electronic devices, and high electron mobility transistors. This article provides an overview of the recent progress made to these materials' electrical properties with particular emphasis on the advancements in the molecular beam epitaxy approaches for their synthesis, and defect control.