  Lead-halide perovskites emerged as novel semiconducting materials suitable
for a variety of optoelectronic applications. However, fabrication of reliable
perovskite field-effect transistors (FETs), the devices necessary for the
fundamental and applied research on charge transport properties of this class
of materials, has proven challenging. Here we demonstrate high-performance
perovskite FETs based on epitaxial, single crystalline thin films of cesium
lead bromide (CsPbBr3). An improved vapor-phase epitaxy has allowed growing
truly large-area, atomically flat films of this perovskite with excellent
structural and surface properties. FETs based on these CsPbBr3 films exhibit
textbook transistor characteristics, with a very low hysteresis and high
intrinsic charge carrier mobility. Availability of such high-performance
devices has allowed the study of Hall effect in perovskite FETs for the first
time. Our magneto-transport measurements show that the charge carrier mobility
of CsPbBr3 FETs increases on cooling, from ~ 30 cm2V-1s-1 at room temperature,
to ~ 250 cm2V-1s-1 at 50 K, exhibiting a band transport mostly limited by
phonon scattering. The epitaxial growth and FET fabrication methodologies
described here can be naturally extended to other perovskites, including the
hybrid ones, thus representing a technological leap forward, overcoming the
performance bottleneck in research on perovskite FETs.
