The Study On Mn-Co-Ni-O Thermal Sensitive Thin Films And Uncooled Infrared Detectors

Uncooled infrared detectors have been widely applied in infrared imaging,space science and technology,biology,medicine,environmental protection and other fields.The development of high-performance,broadband,large-scale integration of uncooled infrared detectors has become a research hotspot in recent years.Transition metal oxides Mn-Co-Ni-O thin film material has the advantages of large negative temperature coefficient of resistivity,broad spectral response range and long-term stability,which is suitable for the preparation of broadband and high performance uncooled infrared detector.However,Mn-Co-Ni-O thin film materials have not been widely used due to high preparation temperature and poor device performance.This paper aims to solve the problems of large-scale application of Mn-Co-Ni-O thin film,and the main contents and innovation points are presented as follows:1.The post-annealing effects on the microstructure,surface morphology and electrical properties of the low-temperature prepared Mn_1.56Co_0.96Ni_0.48O₄(MCN)thin film were studied.Mn_1.56Co_0.96Ni_0.48O₄(MCN)thin films were prepared by radio frequency magnetron sputtering at a relatively low temperature(450?),and the films were annealed at 450?,600?and 750?for 20 min respectively.The structural and surface morphology properties were characterized and the results indicated post annealing had important impact on crystallinity and grain size of the films.Temperature dependent resistivity test revealed that the MCN films annealed at 450?possesses the lowest resistivity(326?·cm)and favorable negative temperature coefficient of resistivity(-3.4%/K),the small polaron of the MCN films follow the nearest neighbor hopping model.The method of low-temperature(450?)sputtering MCN film is expected to be compatible with standard silicon industry process,which has great significance for developing MCN linear or focal plane detector.2.The effects of deposition temperature on microstructure,cation distribution and electrical properties of Mn_1.56Co_0.96Ni_0.48O₄(MCN)thin films were studied.MCN thin films have been deposited at 200?,400?and 750?by radio frequency magnetron sputtering.The crystallinity properties and surface morphologies of the films are greatly influenced by the deposition temperature according to the XRD and FESEM results.The ionic valence states of Mn,Co and Ni were observed by X-ray photoelectron spectroscopy(XPS),the cations distribution and formulas of the MCN films are determined.The Mn³⁺/Mn⁴⁺ratio increases with the higher deposition temperature,and the films deposited at 400?shows maximum concentration of Mn³⁺/Mn⁴⁺pairs.The results of electrical properties reveal that the resistivity of the MCN films falls down with increasing deposition temperature,while all films possess similar characteristic temperature and activation energy.The deposition temperature dependent resistivity mechanism of the MCN films was further analyzed and discussed based on the crystallinity and XPS results.Deposition temperature effects on MCN films were studied in this work,which is valuable to prepare high quality MCN films.3.The optical and electrical performance of Mn_1.5Co₁Ni_0.5O₄ thin film were enhanced by co-doping Cu and Sc elements.We prepared undoped Mn_1.5Co₁Ni_0.5O₄and Cu and Sc co-doped Mn_1.5Co₁Ni_0.25Cu_xSc_0.25-xO₄(x=0.05,0.1,0.15)films on Al₂O₃substrate by chemical solution deposition method.The crystallinity,surface morphologies,electrical transport property,optical property,and 1/f noise property of these films are characterized.The absolute temperature coefficient of resistance and characteristic temperature of the Mn_1.5Co₁Ni_0.25Cu_0.15Sc_0.1O₄film are higher than that of Mn_1.5Co₁Ni_0.5O₄ film,while its resistivity of 250?·cm at 295 K is half of that Mn_1.5Co₁Ni_0.5O₄ film.The transmittance and reflectance spectra of the films are measured and analyzed in the range of 0.55-2.0?m,all the films show similar absorption structures in the measured spectrum.The 1/f noise of the co-doped Mn_1.5Co₁Ni_0.5O₄ films decreases significantly.The(?/n)^0.5/|TCR|value of the Mn_1.5Co₁Ni_0.25Cu_0.15Sc_0.1O₄reaches 2.3×10^-12 cm^1.5 K/%at 295 K,which is two orders lower than that of Mn_1.5Co₁Ni_0.5O₄ film.This study discovered a thermosensitive material with excellent performance,which is expected to be applied to high performance uncooled infrared detectors.4.Study on the performance and infrared imaging of uncooled infrared detector with uniform spectral response in ultra-broadband.The Mn_1.56Co_0.96Ni_0.48O₄(MCN)thin film with low resistivity(131?·cm)and negative temperature coefficient of resistivity(-3.1%/K)was grown by RF magnetron sputtering at room temperature.Based on the MCN film and a commercial organic thin film,an ultra-broadband infrared detector with uniform spectral response has been achieved,the spectral response range of 1.3-27?m(SWIR-VLWIR)with the heterogeneity less than 5%.Meanwhile,an MCN linear array detector was designed and fabricated.The average responsivity and detectivity of all detection elements in the device are 260 V W^-1and 1×10⁸ Jones,and the response time is 9.9 ms.The ultra-broadband MCN linear detector with uniform spectral response is applied for authentic infrared imaging,which verifies the significant advantages of this imaging method in application.The results solve the difficulty of infrared photodetector possesses both ultra-broadband and uniform spectral response,and develops an imaging method with higher detection rate and recognition rate.