Modulated in-plane carrier distribution of oxide two-dimensional electron gas systems by light assisted electrostatic gating

The oxide two-dimensional electron gases (2DEGs) have been intensively studied for both fundamental and applied research over the past decade. It is known that the electrostatic and optical gating can both effectively modulate the transport behavior of 2DEG. However, the in-plane carrier distribution under the light assisted electrostatic gating is scarcely studied. In this study, we systematically investigate this problem in the 3d and 5d oxide-based 2DEGs samples, and observe strong lateral photovoltaic effect (LPE) in both of the 2DEGs. Remarkably, the lateral voltage is strongly dependent on the gating electrical field especially in the 5d oxide-based 2DEGs and its signs are absolutely reversed as the bias voltage becomes negative. Through systematic research, it is found that the leak current caused by light assisted electrostatic gating, strongly affects the in-plane carrier distribution. These results have significance for fundamental research and device application based on the photovoltaic effect of oxide 2DEGs.