skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Electron mobility in monolayer WS2 encapsulated in hexagonal boron-nitride
We report electron transport measurements in dual-gated monolayer WS2 encapsulated in hexagonal boron-nitride. Using gated Ohmic contacts that operate from room temperature down to 1.5 K, we measure the intrinsic conductivity and carrier density as a function of temperature and gate bias. Intrinsic electron mobilities of 100 cm2/(V s) at room temperature and 2000 cm2/(V s) at 1.5 K are achieved. The mobility shows a strong temperature dependence at high temperatures, consistent with phonon scattering dominated carrier transport. At low temperature, the mobility saturates due to impurity and long-range Coulomb scattering. First-principles calculations of phonon scattering in monolayer WS2 are in good agreement with the experimental results, showing we approach the intrinsic limit of transport in these two-dimensional layers.  more » « less
Award ID(s):
1720595
PAR ID:
10474926
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
AIP Publishing
Date Published:
Journal Name:
Applied Physics Letters
Volume:
118
Issue:
10
ISSN:
0003-6951
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; (, Journal of Applied Physics)
    We report the effect of remote surface optical (RSO) phonon scattering on carrier mobility in monolayer graphene gated by ferroelectric oxide. We fabricate monolayer graphene transistors back-gated by epitaxial (001) Ba0.6Sr0.4TiO3 films, with field effect mobility up to 23 000 cm2 V−1 s−1 achieved. Switching ferroelectric polarization induces nonvolatile modulation of resistance and quantum Hall effect in graphene at low temperatures. Ellipsometry spectroscopy studies reveal four pairs of optical phonon modes in Ba0.6Sr0.4TiO3, from which we extract RSO phonon frequencies. The temperature dependence of resistivity in graphene can be well accounted for by considering the scattering from the intrinsic longitudinal acoustic phonon and the RSO phonon, with the latter dominated by the mode at 35.8 meV. Our study reveals the room temperature mobility limit of ferroelectric-gated graphene transistors imposed by RSO phonon scattering. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; (, Advanced Materials)
    Abstract The first experimental realization of the intrinsic (not dominated by defects) charge conduction regime in lead‐halide perovskite field‐effect transistors (FETs) is reported. The advance is enabled by: i) a new vapor‐phase epitaxy technique that results in large‐area single‐crystalline cesium lead bromide (CsPbBr3) films with excellent structural and surface properties, including atomically flat surface morphology, essentially free from defects and traps at the level relevant to device operation; ii) an extensive materials analysis of these films using a variety of thin‐film and surface probes certifying the chemical and structural quality of the material; and iii) the fabrication of nearly ideal (trap‐free) FETs with characteristics superior to any reported to date. These devices allow the investigation of the intrinsic FET and (gated) Hall‐effect carrier mobilities as functions of temperature. The intrinsic mobility is found to increase on cooling from ≈30 cm2V−1s−1at room temperature to ≈250 cm2V−1s−1at 50 K, revealing a band transport limited by phonon scattering. Establishing the intrinsic (phonon‐limited) mobility provides a solid test for theoretical descriptions of carrier transport in perovskites, reveals basic limits to the technology, and points to a path for future high‐performance perovskite electronic devices. 
    more » « less
  3. ; ; ; ; ; ; ; ; (, Applied Physics Letters)
    AlScN is attractive as a lattice-matched epitaxial barrier layer for incorporation in GaN high electron mobility transistors due to its large dielectric constant and polarization. The transport properties of polarization-induced two-dimensional (2D) electron gas of densities of ∼2×1013/cm2 formed at the AlScN–GaN interface is studied by Hall-effect measurements down to cryogenic temperatures. The 2D electron gas densities exhibit mobilities limited to ∼300 cm2/V s down to 10 K at AlScN/GaN heterojunctions. The insertion of a ∼2 nm AlN interlayer boosts the room temperature mobility by more than five times from ∼300 cm2/V s to ∼1573 cm2/V s, and the 10 K mobility by more than 20 times to ∼6980 cm2/V s at 10 K. These measurements provide guidelines to the limits of electron conductivities of these highly polar heterostructures. 
    more » « less
  4. ; ; ; ; ; (, APL Materials)
    The wide-gap semiconducting perovskite BaSnO3 has attracted attention since the discovery of outstanding mobility at high electron densities, spurred on by potential applications in oxide, transparent, and power electronics. Despite progress, much remains to be understood in terms of mobility-limiting scattering in BaSnO3 thin films and thus mobility optimization. Here, we apply solid-state ion-gel-based electrolyte gating to electrostatically control electron density over a wide range (1018 cm−3 to >1020 cm−3) in BaSnO3 films. Temperature- and gate-voltage-dependent transport data then probe scattering mechanisms and mobility vs electron density alone, independently of sample-to-sample defect density variations. This is done on molecular-beam-epitaxy- and sputter-deposited films as a function of thickness, initial chemical doping, and initial mobility. Remarkably universal behavior occurs, the mobility first increasing with electron density to ∼1020 cm−3 before decreasing slightly. This trend is quantitatively analyzed at cryogenic and room temperatures using analytical models for phonon, ionized impurity, charged dislocation, surface/interface roughness, and electrolyte-induced scattering. The mobility maximum is thus understood to arise from competition between charged impurity/dislocation scattering and electrolyte scattering. The gate-voltage-induced mobility enhancement is found as large as 2000%, realizing 300 K mobility up to 140 cm2 V−1 s−1. This work thus significantly advances the understanding of mobility-limiting scattering processes in BaSnO3, resulting in outstanding room temperature mobilities. 
    more » « less
  5. ; ; ; ; ; ; ; ; ; ; et al (, Applied Physics Letters)
    We report controlled silicon doping of Ga2O3 grown in plasma-assisted molecular beam epitaxy. Adding an endplate to the Si effusion cell enables the control of the mobile carrier density, leading to over 5-orders of magnitude change in the electrical resistivity. Room temperature mobilities >100  cm2/V s are achieved, with a peak value >125  cm2/V s at a doping density of low-1017/cm3. Temperature-dependent Hall effect measurements exhibit carrier freeze out for samples doped below the Mott criterion. A mobility of 390  cm2/V s is observed at 97  K. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email