  Correlated electron systems are among the centerpieces of modern condensed
matter sciences, where many interesting physical phenomena, such as
metal-insulator transition and high-Tc superconductivity appear. Recent efforts
have been focused on electrostatic doping of such materials to probe the
underlying physics without introducing disorder as well as to build
field-effect transistors that may complement conventional semiconductor
metal-oxide-semiconductor field effect transistor (MOSFET) technology. This
review focuses on metal-insulator transition mechanisms in correlated electron
materials and three-terminal field effect devices utilizing such correlated
oxides as the channel layer. We first describe how electron-disorder
interaction, electron-phonon interaction and/or electron correlation in solids
could modify the electronic properties of materials and lead to metal-insulator
transitions. Then we analyze experimental efforts toward utilizing these
transitions in field effect transistors and their underlying principles. It is
pointed out that correlated electron systems show promise among these various
materials displaying phase transitions for logic technologies. Furthermore,
novel phenomena emerging from electronic correlation could enable new
functionalities in field effect devices. We then briefly review unconventional
electrostatic gating techniques, such as ionic liquid gating and ferroelectric
gating, which enables ultra large carrier accumulation density in the
correlated materials which could in turn lead to phase transitions. The review
concludes with a brief discussion on the prospects and suggestions for future
research directions in correlated oxide electronics for information processing.
