Effect of ultraviolet radiation on slow-relaxation processes in ferroelectric capacitance structures

Abstract

Articles you may be interested inModification of energy band alignment and electric properties of Pt/Ba0.6Sr0.4TiO3/Pt thin-film ferroelectric varactors by Ag impurities at interfaces Suppression of slow capacitance relaxation phenomenon in Pt/Ba0.3Sr0.7TiO3/Pt thin film ferroelectric structures by annealing in oxygen atmosphere Appl. Phys. Lett.The effects of ultraviolet ͑UV͒ irradiation on the relaxation processes in Ba 0.3 Sr 0.7 TiO 3 thin film capacitors were experimentally investigated in a range of wavelengths = ͑310-400͒ nm. It was observed that irradiation with a specific wavelength reduces the time of slow capacitance relaxation up to three orders of magnitude in comparison with relaxation time in the "dark" regime. It was also observed that at a certain wavelength of UV irradiation there was a maximum in the leakage current of the capacitors. This wavelength corresponded exactly with a minimum in the relaxation time of the capacitance. It was shown that the decrease in the ferroelectric film thickness resulted in a shift in ͑͒minima and I͑͒maxima towards the shorter wavelengths. Phenomena observed are analyzed using Bouguer's law.

Optimizing Strontium Ruthenate Thin Films for Near-Infrared Plasmonic Applications

“…Their concentration reduces with the increase of the O 2 deposition pressure and improvement of the SRO film crystal structure. This is further confirmed by the measured extremely low carrier mobility in films grown at O 2 deposition pressure below 50 mTorr, as the non-equilibrium charge carriers are usually trapped by the defects24. The carrier concentrations measured for the films grown at O 2 deposition pressure above 50 mTorr are in agreement with the previously observed values2526.…”

Injected charge as a cause of the slow dielectric relaxation in thin film Pt/(Ba,Sr)TiO3/Cu structures

“…Measurements of the UV absorption coefficient, carried out with BSTO film-based planar structures, have revealed a band-edge tailing (%0.1 eV) that can be attributed to the high density of shallow traps. 7 Apart from the shallow traps, there are deep trap centers that can be formed, in particular, by interstitial oxygen atoms incorporated during the deposition of a BSTO film in an oxygen atmosphere at T ¼ 675 C and by complexes formed by O-vacancies and metal ions. 28,29 For BSTO films, trap centers with different energy spacings (E t ) from the conduction band bottom have been reported: 0.2 eV and 1.31 eV, 30 0.3 eV, 0.55 eV, and 0.88 eV, 29 0.335 eV, 31 0.51 eV, 13 and 0.83 eV.…”

“…However, BSTO films show a slow dielectric relaxation, which is the critical problem in the case of the pulse-controlled operation mode, when the capacitance does not return to its initial value after the end of a control voltage pulse, but slowly relaxes in the course of time. [4][5][6][7] This results both in the ambiguity in the controlled phase, frequency, or delay and in their variation with the control-pulse parameters (amplitude, duration, repetition frequency). 7,8 An understanding of the physical mechanisms of the slow dielectric relaxation in perovskite-oxide films and a search for the possibility of speeding-up the relaxation are important for the development of not only fast microwave devices, but also high-capacity ferroelectric memories, because the same mechanisms may be responsible for the polarization fatigue.…”

“…[4][5][6][7] This results both in the ambiguity in the controlled phase, frequency, or delay and in their variation with the control-pulse parameters (amplitude, duration, repetition frequency). 7,8 An understanding of the physical mechanisms of the slow dielectric relaxation in perovskite-oxide films and a search for the possibility of speeding-up the relaxation are important for the development of not only fast microwave devices, but also high-capacity ferroelectric memories, because the same mechanisms may be responsible for the polarization fatigue. 9,10 Two main mechanisms responsible for the slow dielectric relaxation in BSTO films have been discussed: (i) formation of a p-n junction due to the oxygen vacancy redistribution in the biasing electric field 4,5,11,12 and (ii) space charge (SC) formation due to the electron injection from electrodes, followed by the capture of electrons by deep traps in the band gap.…”

Impact of total ionizing dose irradiation on electrical property of ferroelectric-gate field-effect transistor

“…Recently, intensive experimental research has been performed to investigate the radiation effect of ferroelectric thin films. [5][6][7][8][9][10][11][12][13][14][15][16][17] For example, Menou et al 8 had demonstrated that the electrical characteristics of Pt/SrBi 2 Ta 2 O 9 (SBT)/Pt ferroelectric capacitor changed significantly during or after irradiation. In their work, both "fatigue-like" (polarization reduction) and/or "imprint-like" (voltage shift) phenomena were observed.…”