Visible-light-enhanced gating effect at the LaAlO3/SrTiO3 interface

Abstract

Electrostatic gating field and light illumination are two widely used stimuli for semiconductor devices. Via capacitive effect, a gate field modifies the carrier density of the devices, while illumination generates extra carriers by exciting trapped electrons. Here we report an unusual illumination-enhanced gating effect in a two-dimensional electron gas at the LaAlO 3 /SrTiO 3 interface, which has been the focus of emergent phenomena exploration. We find that light illumination decreases, rather than increases, the carrier density of the gas when the interface is negatively gated through the SrTiO 3 layer, and the density drop can be 20 times as large as that caused by the conventional capacitive effect. This effect is further found to stem from an illumination-accelerated interface polarization, an originally extremely slow process. This unusual effect provides a promising controlling of the correlated oxide electronics in which a much larger gating capacity is demanding due to their intrinsic larger carrier density.

When two become one: An insight into 2D conductive oxide interfaces

“…Furthermore, we have also recently being able to control the carrier density by shining light using the photoconductivity effect in addition to the back-gate [30]. We found that light illumination decreases, rather than increases, the carrier density of the gas when the interface is negatively gated through the STO layer, and the density drop can be 20 times as large as that caused by the conventional capacitive effect.…”

“…Owing to the greater sensitivity of their electronic properties and because of the wider range of phenomena that can be observed in these interfaces, the implications for basic physics and technological application using oxide heterostructures are likely to be enormous. [27], field-induced metal-insulator transition [29], and optical sensitivity [30]. The mechanism underlying the two-dimensional electron gas (2DEG) at the interface between two insulating oxides of LAO and STO is still unclear and under a debate.…”

Effect of Sr-doping of LaMnO3 spacer on modulation-doped two-dimensional electron gases at oxide interfaces

“…7 Therefore the 2DEG of STO interfaces exhibits a large number of interesting properties, such as 2D superconductivity 8,9 , magnetism 10 , and metal-insulator transitions 11,12 . However, the relatively low electron mobility (~1000 cm 2 V -1 s -1 at 2 K) and the high sheet carrier concentration (10 13 -10 14 cm -2 ) of typical STO 2DEGs have hindered the applications such as demonstration of quantum Hall effects [13][14][15] or the achievement of sizable field effects 16 .…”

Scavenging of oxygen vacancies at modulation-doped oxide interfaces: Evidence from oxygen isotope tracing

“…Besides, STO is also a model system for mixed ionic and electronic conductors at high temperatures, due to the presence of unintentional dopants (typically Fe, Al, and Mn) which act as acceptor type impurities [3]. In recent years, STO has attracted increasing attention for application in oxide electronics as active materials, particularly upon the discovery of a two-dimensional electron gas (2DEG) at the STO surface [4] or its interface with another band insulator, such as perovskite LaAlO3 (LAO) [5] or spinel γ-Al2O3 (GAO) [6].The 2DEG of STO interface to another oxide insulator has drawn extensive attention because of the emergent properties which are not observed in the bulk counterparts, such as 2D superconductivity [7,8], magnetism [9], quantum Hall effect [10], as well as light enhanced field effects [11]. On the…”

“…The 2DEG of STO interface to another oxide insulator has drawn extensive attention because of the emergent properties which are not observed in the bulk counterparts, such as 2D superconductivity [7,8], magnetism [9], quantum Hall effect [10], as well as light enhanced field effects [11]. On the…”