Study On The Photoelectric Properties Of Perovskite Titanate

Perovskite oxides is a kind of oxide material with abundant physical and chemical properties and application prospect,the titanates with perovskite structure have important applications in space exploration,material analysis and environment monitoring.Light is an important method for studing the properties of perovskite oxides through which controllable electrodes and holes could be doped without changing the stoichiometric ratio and crystal structure of the oxides.In this paper,the physical properties of titanate under UV irradiation were studied.There are mainly two aspects in this paper: 1.The temperature-dependent resistance switching phenomenon has been found in strontium titanate crystal.2.A self-powered visible blind UV detector based on ferroelectric perovskite oxide has been prepared.The main contents and conclusions of this paper are displayed as follows:1.The resistance switching phenomena were studied in strontium titanate single crystals.With the assistance of 375 nm ultraviolet continuous laser,the resistance hysteresis loops appear at a certain temperature ranging from 340 K to 520 K and reached the maximum value at 420 K.2.These resistance switching phenomena only exist in samples with enough oxygen vacancies,which is confirmed by spherical aberration-corrected scanning transmission electron microscopy measurements,demonstrating an important role played by oxygen vacancies.Positively charged oxygen vacancies become mobile triggered by external electric field,and the resistance switching effect emerges.Two resistance states are produced under the cooperative effect of built-in field and external field.3.We employed BaTiO3(BTO)single crystals with a bandgap of 3.2 eV for the realization of a self-driven ultraviolet detector,by utilizing the ferroelectric properties of BTO.We found that the sign of the photocurrent can be reversed by flipping the ferroelectric polarization,which makes the photodetector suitable for electrical manipulation.4.The photoelectric performance of this photodetector was systematically investigated in terms of rectification character,stability of short-circuit photocurrent,spectral response,and transient photoelectric response.Particularly,the self-driven photodetectors based on BTO showed an ultrafast response time about 200 ps.It is expected that the present work can provide a route for the design of photodetectors based on ferroelectric oxides.