Time-dependent resistance of quasi-two-dimensional electron gas on KTaO3

Abstract

For most conductive materials, resistance remains constant over time in the absence of external physical stimulation. Here, we report the time-dependent resistance of a quasi-two-dimensional electron gas (Q2DEG) on a KTaO3 substrate. Ar+-ion bombardment is used to achieve a Q2DEG of high density. Such a Q2DEG shows a linear increase in resistance with time without further physical stimulus. Both the resistance and its increase rate can be determined by the beam voltage of Ar+ bombardment. Furthermore, we find that light illumination strongly influences the increase rate of resistance, with the effect depending primarily on the wavelength of incident light. The Hall effect reveals that this phenomenon can be attributed to the spontaneous decrease in carrier density over time due to the migration of oxygen vacancies. Our work offers a pathway toward a self-excited resistance timer in a Q2DEG system.