Non-volatile electrical and optical resistive switching in 2D electron gases at oxide
heterostructures.
Dott. Fabio Miletto Granozio
CNR-SPIN, UOS Napoli
Complesso universitario di Monte Sant’Angelo, Via Cinthia, 80126 Napoli
E-mail:
A 2D electron gases at oxide interfaces is a perfect example of transparent conducting
system, as discovered about a decade ago. A nm-thick layer of electrons showing low
temperature mobilities exceeding 10
4
cm
2
/Vs is spontaneously formed at the interface
between two materials, SrTiO
3
and LaAlO
3
, with optical gaps exceeding 3eV.
The combined effect of a back-gate voltage and of light has been analyzed on a number of
oxide 2DEG field-effect devices. We show that an appropriate procedure based on single-
gate-voltage pulses, applied below 100K, can drive our lowest-carrier-density samples to an
insulating state, which is persistent in zero gate voltage and dark. This state can be destroyed
by a relatively modest dose of visible-range photons, which cause a sudden collapse of the
system back to the metallic ground state, with a resistivity decrease exceeding four orders of
magnitude. The system is repeatedly switchable between the ON and OFF states by the
alternate application of voltage and light pulses. Different intermediate resistance states can
be stabilized by a proper tuning of the control parameters, hinting some potential for the
design of multilevel devices. A model describing our findings in terms of a controlled
electron transfer between mobile and localized interfacial states is proposed. We show that
the actual device resistance depends on the history of the gate current and of the photon flux.
The analogy with memristive devices is discussed.
I 30
-154-
