基于铝纳米颗粒修饰的非晶氧化镓薄膜日盲紫外探测器

High performance amorphous Ga_(2)O_(3) thin film solar blind ultraviolet photodetectors decorated with Al nanoparticles

近年来,宽带隙半导体材料氧化镓在日盲紫外探测领域的应用引起了广泛关注.本文基于溶液法制备了非晶氧化镓薄膜,采用紫外光退火的方式降低了薄膜的制备温度,并且通过铝颗粒修饰氧化镓薄膜表面,提升了氧化镓紫外探测器的性能.紫外退火的方式可将氧化镓薄膜的制备温度降至300℃,有望实现柔性器件的制备.当沉积铝膜厚度在3—5 nm时,可获得分布均匀、直径为2—3 nm的铝颗粒,经修饰的氧化镓薄膜表现出优秀的光电响应性能和日盲探测特性.在254nm光照下,最大光暗电流比可达2.55×10^(4),在紫外波段的抑制比I_(254nm)/I_(365nm)为2.2×10^(4).最佳的探测器响应度和探测率分别为0.771 A/W和1.13×10^(11)Jones,相比于未做修饰的氧化镓紫外探测器提升了约34倍和36倍.然而,铝纳米颗粒的修饰也会引入部分缺陷态,导致氧化镓光电探测器响应下降时间的增大.

Gallium oxide(Ga_(2)O_(3)) as a wide bandgap semiconductor material has attracted much attention in the field of solar blind ultraviolet photo detect ion recently.Localized surface plasmon resonance is considered an effective way to improve the performance of optoelectronic devices by decorating the materials with metal particles.Al nanoparticle is a potential candidate for ultraviolet photodetectors because its suitable resonance wavelength is located in the ultraviolet wavelength range.In this work,the preparation temperature of the Ga_(2)O_(3)thin film is reduced by ultraviolet photo-annealing,and the amorphous Ga_(2)O_(3)thin film is prepared by using the solution method.In addition,aluminum(Al) nanoparticles are used to decorate the surface of Ga_(2)O_(3)thin film through thermal evaporation of aluminum film and then annealing,which improves the optoelectrical performance in the solar-blind wavelength spectrum.The X-ray diffraction(XRD) is employed to demonstrate the amorphous Ga_(2)O_(3)thin film.The surface roughness and the diameters of Al nanoparticles are analyzed by atomic force microscope(AFM).When the thickness of the deposited Al layer is about 3-5 nm,Al particles with the diameters in a range of 2-3 nn can be obtained.When the thickness of the deposited Al layer is more than7 nm,Al nanoparticles turn into the particles with non-identical diameters and distribute in the form of agglomeration.Transmittance spectrum and absorption spectrum are employed to characterize the optical properties.The bandgaps of different samples are obtained,and the results are consistent with the theoretical ones.The Ga_(2)O_(3)thin film shows excellent optoelectrical performance and solar blind rejection ratio.Under254 nm illumination,the maximum photo-to-dark current ratio is 2.55×10^(4),and the rejection ratio of I_(254nm)/I_(365nm) is 2.2×10^(4).The best responsivity and detectivity of prepared samples are 0.771 A/W and 1.13×10^(11)Jones,which are about 34 times and 36 times higher than those without Al decoration.The improvement is attributed to the scattering effect of surface Al nanoparticles for illumination,which enhances the Ga_(2)O_(3)thin film absorption of solar blind ultraviolet light.Meanwhile,owing to the localized surface plasma resonance,the local electromagnetic fields generated near the Al nanoparticles promote the transfer of carriers in the film.Furthermore,the point about how the Al nanoparticles decorated on the surface of Ga_(2)O_(3)thin film influence the time response is also discussed in this work.As a result,the introduction of defect states will lead to an increase of fall time due to the Al deposition.In this work,the effect of Al nanoparticles decoration on the optoelectrical performance of amorphous Ga_(2)O_(3)thin film solar blind ultraviolet photodetectors is studied based on a simple preparation,which provides a possible pathway for developing the flexible solar blind electronic devices in the future.