Non-Ohmic Variable-Range Hopping and Resistive Switching in SrTiO_{3} Domain Walls

Area of Science:

• Condensed Matter Physics
• Materials Science
• Electrical Engineering

Background:

• Strontium titanate (SrTiO3) is a versatile perovskite oxide with complex electrical properties.
• Understanding charge transport mechanisms in insulating SrTiO3 is crucial for electronic device applications.

Purpose of the Study:

• To investigate electric field driven conductivity in insulating SrTiO3 at low temperatures.
• To characterize negative differential conductance and resistive switching phenomena.
• To elucidate the underlying charge transport mechanisms, distinguishing between different hopping models.

Main Methods:

• Electrical transport measurements on SrTiO3 samples at low temperatures.
• Application of a wide range of electric fields to observe conductivity.
• Analysis of current-voltage characteristics to identify conduction mechanisms (e.g., variable range hopping, space-charge-limited currents).

Main Results:

• Observation of electric field driven conductivity with negative differential conductance and resistive switching.
• Current-voltage characteristics at high electric fields follow I=I0exp[-(E*/E)1/2], indicative of variable range hopping with a Coulomb gap.
• Unambiguous discrimination between Shklovskii and Mott hopping models based on electric field exponents.
• Determination of charge mobility limits between 17 and 210 cm2/Vs under space-charge-limited current conditions.

Conclusions:

• The study provides clear evidence for electric field driven conduction phenomena in insulating SrTiO3.
• Variable range hopping with a Coulomb gap in domain walls is identified as a key transport mechanism.
• The findings offer insights into charge transport and mobility in SrTiO3, relevant for advanced electronic applications.