Abstract
Materials with persistent photoconductivity (PPC) experience an increase in conductivity upon exposure to light that persists after the light is turned off. Although researchers have shown that this phenomenon could be exploited for novel memory storage devices, low temperatures (below 180 K) were required. In the present work, two-point resistance measurements were performed on annealed strontium titanate (SrTiO3, or STO) single crystals at room temperature. After illumination with sub-gap light, the resistance decreased by three orders of magnitude. This markedly enhanced conductivity persisted for several days in the dark. Results from IR spectroscopy, electrical measurements, and exposure to a 405 nm laser suggest that contact resistance plays an important role. The laser was then used as an “optical pen” to write a low-resistance path between two contacts, demonstrating the feasibility of optically defined, transparent electronics.
Highlights
STO is a complex oxide semiconductor with the perovskite structure and an indirect band gap of 3.2 eV1, 2
Prior work on large persistent photoconductivity (PPC) has focused on DX centers, deep-level defects that involve the displacement of a donor impurity[16, 17]
Resistance has a nonlinear dependence on free-carrier concentration or that interface traps are filled during the first few seconds of light exposure
Summary
STO is a complex oxide semiconductor with the perovskite structure and an indirect band gap of 3.2 eV1, 2. Because DX centers exhibit PPC, optical exposure increases the free-carrier density and changes the refractive index[20]. Room temperature PPC was utilized to selectively reduce two-point resistance values. Typical PL spectrum of STO, after annealing and light exposure.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
