Photoinduced Negative Differential Resistivity and Gunn Oscillations in SrTiO3

Area of Science:

• Materials Science
• Solid State Physics
• Oxide Electronics

Background:

• Strontium titanate (SrTiO3) is a perovskite oxide with significant potential in oxide electronics.
• Its photoelectric activity at low temperatures overlaps with the quantum paraelectric state, exhibiting unique characteristics.

Purpose of the Study:

• To investigate the photoelectric properties of SrTiO3 under photoexcitation.
• To understand the mechanisms behind non-linear photocarrier transport and negative resistance.

Main Methods:

• Photoexcitation of SrTiO3 with above band gap energy photons.
• Analysis of photocarrier transport and current-voltage characteristics.
• Investigation of electron intervalley transfer phenomena.

Main Results:

• Photoexcitation induces non-linear photocarrier transport and voltage-controlled negative resistance in SrTiO3.
• An intervalley transfer of photo-induced electrons is identified as the cause of negative resistance.
• The observed negative resistance leads to unstable photocurrent and spontaneous low-frequency Gunn-like oscillations.

Conclusions:

• SrTiO3 exhibits complex photoelectric behavior driven by intervalley electron transfer.
• The material demonstrates potential for novel electronic devices through phenomena like Gunn-like oscillations.
• Understanding these low-temperature photoelectric effects is crucial for advancing oxide electronics.