Photoluminescence, Photocurrent, and Phase-Transition Correlations in SrTiO3

Abstract

Properties of stacked SrTiO3/Al2O3 metal-insulator-metal capacitorsPhotoluminescence emanating from "pure" high resistivity SrTiO" has been examined between 4000 and 13 000 A as a function of temperature and 3650 A irradiation. One strong narrow peak: (7929 A at 95°K; half-width ~1 A) and 9 associated peaks (7852, 8005, 8051, 8098, 8280, 8304, 8469, 8574, 8726 A), each of which exhibit maximum intensity at 35° and 95°K, which are within the temperature ranges associated with the ferroelectric-paraelectric transition, and the tetragonal-cuhic transition, respectively. As this emission extinguishes below 35°K, an asymmetric structureless broadband emission begins, which extends from ""4200-,,,,8000 A, and peaks near 5000 A. Concurrent photocurrent measurements show: a maximum at 105°K and a minimum at 35°K; the existence of extensive trapping effects, including long-duration (hours to days) dark-current relaxation, a field-induced persistent internal polarization (due to spacial separation of trapped electrons and holes), and an interaction between irradiation and ferroelectric hysteresis. Sublinear responses exist common to the photoluminescence peaks and photocurrents at various temperatures, viz. response a:: J~(T) where ! <~ (T) < 1. The behavior ohserved is in part interpretable on the basis of recombination processes via multiple defects.

Structural conditions that leads to photoluminescence emission in SrTiO3: An experimental and theoretical approach

“…8-10͒ when they are excited by radiation energy above the band gap. [11][12][13] Investigations into the temperature dependence of visible emission have demonstrated that this emission band is quenched at temperatures above 110 K.…”

Absorption in a strong-coupling half-filled-band Hubbard chain

“…Stoichiometric SrTi0 3 is an insulator transparent to visible light. At room temperature, it is cubic but undergoes a transition to a tetragonal structure at about Il0K (3). I'lllen strontium titanate is reduced, it takes on a blue color and becomes semiconducting, Strontium titanate displays a number of interesting photochromic and electrochromic properties (4) when doped with metal ions and hence has potentially important electro-optic applications in areas such as image storage, photochromism, and electrochromism.…”

Dynamics of photogenerated nonequilibrium electronic states inAr+-ion-irradiatedSrTiO3

“…The gradual increase in PC on going down from 300 K to 100 K can be elucidated on the basis of e − -h + quasiFermi levels which move through the distributed levels leading to modification in the recombination kinetics 43 , which increases the majority carrier life time on lowering the temperature. The precipitous increase in ∆R P below 100 K must be linked to increase in mobility (µ) or carrier density (n ) or both.…”