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一种Sn掺杂GeSbTe热电薄膜及其制备方法 【EN】Sn doped GeSbTeThermoelectric film and method for manufacturing the same

申请(专利)号:CN202011274935.0国省代码:江苏 32
申请(专利权)人:【中文】江苏科技大学【EN】JIANGSU University OF SCIENCE AND TECHNOLOGY
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摘要:
【中文】本发明公开了一种Sn掺杂Ge2Sb2Te5热电薄膜及其制备方法,以Ge2Sb2Te5和Sn为原料,采用磁控溅射共沉积的方法,在基板上沉积得到Sn掺杂Ge2Sb2Te5热电薄膜。本发明通过材料设计和优选工艺参数,在基板上沉积单层Sn掺杂Ge2Sb2Te5热电薄膜,大幅提高了材料的热电转换效率的同时,能够有效的降低制备纳米Sn掺杂Ge2Sb2Te5薄膜的制造工艺的复杂性与成本性,有利于推广和应用。 【EN】The invention discloses Sn doped Ge2Sb2Te5Thermoelectric thin film and method for preparing the same, with Ge2Sb2Te5And Sn as raw material, and depositing on the substrate to obtain Sn doped Ge by adopting a magnetron sputtering codeposition method2Sb2Te5A thermoelectric thin film. The invention deposits a single layer of Sn doped Ge on a substrate through material design and optimized process parameters2Sb2Te5The thermoelectric film greatly improves the thermoelectric conversion efficiency of the material and can effectively reduce the preparation of the nano Sn doped Ge2Sb2Te5The complexity and the cost of the manufacturing process of the film are favorable for popularization and application.

主权项:
【中文】1.一种Sn掺杂GeSbTe热电薄膜,其特征在于:以GeSbTe和Sn为原料,采用磁控溅射共沉积的方法,在基板上沉积得到Sn掺杂GeSbTe热电薄膜;薄膜材料的化学通式为Sn(GeSbTe),其中,0<x<0.25。 【EN】1. Sn doped GeSbTeA thermoelectric film, characterized by: with GeSbTeAnd Sn as raw material, and depositing on the substrate to obtain Sn doped Ge by adopting a magnetron sputtering codeposition methodSbTeA thermoelectric thin film; the chemical formula of the film material is Sn(GeSbTe)Wherein x is more than 0 and less than 0.25.


说明书

【中文】

一种Sn掺杂Ge2Sb2Te5热电薄膜及其制备方法

技术领域

本发明涉及一种热电薄膜及其制备方法,特别是涉及一种Sn掺杂Ge2Sb2Te5热电薄膜及其制备方法。

背景技术

太阳能、风能、潮汐能等新型能源的出现缓解了能源短缺与环境污染,但还远远不够,寻求更多的新型能源是目前当务之急。从19世纪20年代德国科学家塞贝克发现温差发电效应以来,热电材料作为热能与电能相互转化的新型能源材料,迅速成为了材料学领域的一个新的研究方向。近十年来,随着材料科学、新型半导体材料、纳米科技的不断进步,世界范围内的科学家都在不断探索并开发各种具有使用价值的新型热电材料。温差电池是适用很广的绿色环保型能源,主要通过热电材料的热电效应,将热能与电能直接相互转换,从而实现温差发电,具有体积小、质量轻、坚固无噪音、寿命长、易于控制等优点。

目前,热电转换材料已经应用在国防和高新技术领域,比如航空飞行器、医疗产品、汽车坐垫等;也已经应用在电子技术中,比如电子设备、电子器件以及计算机的冷却等;也已经应用在工业之中,比如汽车冷藏箱、石油探测器、高真空冷阱等。但是,现有技术中已应用的热电材料的热电转化效率普遍不高,能提供的比功率也有限。随着微纳电子学器件、新型微纳机电系统以及微小集成系统的发展,利用热电材料的热电转换功能,为微纳米集成电路等功耗较低的系统提供不间断能源,成为一种可能,更是一种发展与应用的方向,这很大地促进了热电薄膜材料的开发研究。而由于热电材料本身的性质,制造成本较高,转换效率偏低,很难有利于热电器件的大规模使用。

发明内容

发明目的:本发明的目的之一是提供一种Sn掺杂Ge2Sb2Te5热电薄膜,热电转化效率高,成本低;本发明的目的之二是提供一种Sn掺杂Ge2Sb2Te5热电薄膜的制备方法,制备工艺简单,制备得到的薄膜转换效率高,有利于热电器件的大规模使用。

技术方案:本发明提供的一种Sn掺杂Ge2Sb2Te5热电薄膜,其以Ge2Sb2Te5和Sn为原料,采用磁控溅射共沉积的方法,在基板上沉积得到单层Sn掺杂Ge2Sb2Te5热电薄膜;薄膜材料的化学通式为Snx(Ge2Sb2Te5)1-x,其中,0<x<0.25。

优选地,该薄膜的厚度为200~400nm;该厚度下的Sn掺杂Ge2Sb2Te5热电薄膜的热电性能最佳。

现有技术中Ge2Sb2Te5是硫系相变存储材料,其具有较大的电传导、小的能带间隙以及较大的有效质量,本发明突破性的选用Ge2Sb2Te5材料进行制备热电材料,并选用掺入Sn元素,磁控溅射共沉积得到Sn掺杂的Ge2Sb2Te5热电薄膜材料,其热电转化效率高,且制备成本低。

本发明还提供了一种Sn掺杂Ge2Sb2Te5热电薄膜的制备方法,具体包括如下步骤:

(1)在磁控溅射系统中,将Sn靶材置于磁控射频溅射靶位,将Ge2Sb2Te5靶材置于磁控直流溅射靶位上,关闭腔室门;

(2)对腔室进行抽真空,后通入惰性气体,气体流量设置在20sccm及其以下;

(3)采用溅射共沉积的方法,在基板上沉积Sn掺杂的Ge2Sb2Te5薄膜;

(4)将沉积得到的薄膜在真空退火炉中进行真空退火,得到退火态的Sn掺杂Ge2Sb2Te5热电薄膜。

其中,沉积所用的基板为石英片和硅片;各基板所用于测试的目的不同,硅片可用于测试其掺杂薄膜的物相结构以及截面效果,石英片可用于测试热电参数。

步骤(2)中,抽真空阶段将磁控溅射本底真空度保持在1.0×10-4~4.0×10-4pa,后通入惰性气体将磁控溅射系统的压强设置在0.4~1.0Pa。

为了优化薄膜的热电性能,步骤(3)中,设置Sn靶材的射频溅射功率为20~55W,Ge2Sb2Te5靶材的直流溅射功率设置为50~60W;溅射时间为30~45min;进一步地,设置Sn靶材的射频溅射功率为40~55W。

步骤(4)真空退火温度为200~300℃,退火时间为20~30min。

具体地,上述Sn掺杂Ge2Sb2Te5热电薄膜的制备方法,包括如下步骤:

A、选择纯度为99.99%的Sn靶材和纯度为99.99%的Ge2Sb2Te5靶材作为原料,将Sn靶材和Ge2Sb2Te5靶材分别置于溅射系统的工位靶材架上;

B、将溅射系统本底真空度抽至1.0~4.0×10-4Pa,通入惰性气体,将所述溅射系统的压强控制在0.4~1pa;

C、采用溅射共沉积的方法在硅片和石英基板上沉积Sn掺杂的Ge2Sb2Te5薄膜;

D、将沉积好的薄膜进行热处理,所述温度在200℃~300℃,得到Sn掺杂的Ge2Sb2Te5热电薄膜。

本发明的关键技术环节分别为材料的选取设计及制备工艺条件的控制,两者相辅相成。衡量热电材料性能主要通过一个无量纲的ZT来表征,其中ZT=S2σT/k,其中S为塞贝克系数,σ为电导率,T为绝对温度,K为热导率(T为某一确定温度,不同温度下的ZT值不同)。一般地,热电材料的热电优值是判定一种热电材料能否有效应用于热电器件的重要判断标准,热电材料热电优值小于1将不利于热电器件的应用,具有较低的热电转换价值。而Ge2Sb2Te5是硫系相变存储材料,具有较大的电传导、小的能带间隙以及较大的有效质量,本发明突破性的将其应用于热电薄膜材料,并掺杂Sn,采用磁控溅射共沉积的方法,结合优选地制备工艺,成功制备得到Sn掺杂Ge2Sb2Te5热电薄膜材料,大幅提升了材料的塞贝克系数。

有益效果:

(1)本发明的制备方法是利用控制纳米层厚度预制层方式形成纳米结构的Sn掺杂的Ge2Sb2Te5薄膜,通过调控制备工艺参数,从而调节Sn掺杂的含量,从而形成完整致密的纳米结构的薄膜,大幅度提高了热电薄膜的热电性能。

(2)与现有技术相比,本发明通过材料设计和优选地工艺参数,在基板上沉积单层Sn掺杂Ge2Sb2Te5热电薄膜,大幅提高了材料的热电转换效率的同时,能够有效的降低制备纳米Sn掺杂Ge2Sb2Te5薄膜的制造工艺的复杂性与成本性,有利于推广和应用。

附图说明

图1是沉积态Sn-Ge2Sb2Te5热电薄膜形成示意图。

图2是退火态Sn-Ge2Sb2Te5热电薄膜形成示意图。

图3是Sn-Ge2Sb2Te5热电薄膜XRD图。

图4是Sn-Ge2Sb2Te5热电薄膜的横截面SEM图片。

图5是Sn-Ge2Sb2Te5热电薄膜的表面形貌SEM图片。

图6是Ag-Ge2Sb2Te5热电薄膜的XRD图。

图7是Ag-Ge2Sb2Te5热电薄膜的表面形貌SEM图片。

具体实施方式

下面结合实施例和对比例对本发明进一步地详细描述。

以下实施例和对比例中用到的原料和试剂均为市售。

实施例1:

本实施例中制备Sn掺杂Ge2Sb2Te5热电薄膜。

采用磁控溅射方式镀膜,将纯度为99.99%的Sn和Ge2Sb2Te5靶材安置在磁控溅射腔室的溅射靶位上,以硅片和石英玻璃片作为基底,在基板上沉积得到单层Sn掺杂Ge2Sb2Te5热电薄膜。

制备方法具体包括步骤:

(1)选择纯度为99.99%的Sn靶材和纯度为99.99%的Ge2Sb2Te5靶材作为原料,然后将Sn靶材和Ge2Sb2Te5靶材分别置于溅射系统的工位靶材架上,关闭腔室门,关闭放气阀;即将Sn靶材置于磁控射频溅射靶位,将Ge2Sb2Te5靶材置于磁控直流溅射靶位上。

(2)抽真空,将溅射系统本底真空度抽至1.0×10-4Pa,通入流量为20sccm氩气,将所述溅射系统的压强控制在0.4Pa;

(3)采用磁控溅射共沉积的方法,调整Ge2Sb2Te5靶的功率为60W,Sn靶功率分别设置为20W、30W、40W、50W、55W,在硅片和石英基板上沉积的掺Sn的Ge2Sb2Te5薄膜,沉积时间为45min,即得到沉积态的Sn掺杂Ge2Sb2Te5热电薄膜。

掺Sn的Ge2Sb2Te5薄膜的厚度约为300nm,测得薄膜沉积速率约为6.65nm/min。

(4)将上述共沉积好的薄膜进行热处理,所述热处理的温度为280℃,退火时间为30min,最后得到Sn掺杂Ge2Sb2Te5热电薄膜。

本实施例通过选用单质靶Sn靶和化合物靶Ge2Sb2Te5靶作为原材料,在基板1上共沉积Sn掺杂的Ge2Sb2Te5薄膜2,如图1所示;然后将上述薄膜进行退火,如图2所示;最终形成Sn掺杂Ge2Sb2Te5的热电薄膜3,制备得到的薄膜中,Sn靶功率为20W时,制备得到Sn0.05(Ge2Sb2Te5)0.95热电薄膜;Sn靶功率为30W时,制备得到Sn0.11(Ge2Sb2Te5)0.89热电薄膜;Sn靶功率为40W时,制备得到Sn0.14(Ge2Sb2Te5)0.86热电薄膜;Sn靶功率为50W时,制备得到Sn0.17(Ge2Sb2Te5)0.83热电薄膜;Sn靶功率为55W时,制备得到Sn0.23(Ge2Sb2Te5)0.77热电薄膜。

如图3所示为制备得到的Sn-Ge2Sb2Te5热电薄膜XRD图,图4是Sn-Ge2Sb2Te5热电薄膜的横截面SEM图片,从图3中可以看出Sn元素掺杂进Ge2Sb2Te5结构中,形成单相固溶体,图4为Sn-Ge2Sb2Te5热电薄膜的扫描截面图,其截面厚度为300nm,图5为Sn-Ge2Sb2Te5热电薄膜的表面形貌图,膜层致密性良好。

如下表1所示,为所制备的薄膜的热电性能,表中分别为Sn溅射功率为20W、30W、40W、50W、55W,以及测量温度在723k下测试得到,可以看出随着Sn掺杂功率的提高其塞贝克系数增加,电阻率降低,热导率也随之降低,其功率因数与热电优值得以提升。

表1

对比例:

本对比例制备Ag掺杂Ge2Sb2Te5热电薄膜。

其具体包括步骤:

(1)选择纯度为99.99%的Ag靶材和纯度为99.99%的Ge2Sb2Te5靶材作为原料,然后将Ag靶材和Ge2Sb2Te5靶材分别置于溅射系统的工位靶材架上,关闭腔室门,关闭放气阀;

(2)抽真空,将溅射系统本底真空度抽至1.0×10-4Pa,通入流量为20sccm氩气,将所述溅射系统的压强控制在0.4Pa;

(3)采用磁控溅射共沉积的方法,调整Ge2Sb2Te5靶的功率为60W,Ag靶功率分别设置为6W,8W,10W,12W,在硅片和石英基板上沉积的掺Ag的Ge2Sb2Te5薄膜,沉积时间为50min,即得到沉积态的Ag掺杂Ge2Sb2Te5热电薄膜;薄膜的厚度约为280nm,换算得到薄膜沉积速率为5.6nm/min。

(4)将上述共沉积好的薄膜进行热处理,所述热处理的温度为250℃,退火时间为25min,得到Ag掺杂Ge2Sb2Te5热电薄膜。

本实施例通过选用单质靶Ag靶和化合物靶Ge2Sb2Te5靶作为原材料,在基板上共沉积Ag掺杂的Ge2Sb2Te5薄膜,如图6所示为制备得到的Ag-Ge2Sb2Te5热电薄膜的XRD图,图7为Ag-Ge2Sb2Te5热电薄膜的表面形貌图;从图6可知,当Ag掺杂进入Ge2Sb2Te5晶体结构中,将会有二次相析出,会影响其热电性能;从图7可知,Ag掺杂Ge2Sb2Te5热电薄膜质量较差,并且表面缺陷和空洞增加,膜层表面致密性降低。

如下表2所示为所制备的薄膜的热电性能,表中分别为Ag溅射功率为6W、8W、10W、12W,以及测量温度在723k测试得到的;可以看出Ag掺杂Ge2Sb2Te5热电薄膜的热点优值显著低于Sn掺杂Ge2Sb2Te5热电薄膜;并且,随着掺杂功率继续提高,其热电性能随之下降。

表2

可以看出,掺Ag的热电薄膜质量差,不能用于热电器件,且热电性能较差;而现有技术中已有的热电薄膜的热点优值最大约0.5-0.7,相对于现有技术常用的热电薄膜以及掺Ag的Ge2Sb2Te5热电薄膜,本发明创新地采用Sn掺杂的Ge2Sb2Te5薄膜,得到的热电薄膜可以大幅提高材料的塞贝克系数,薄膜材料的热电性能优异,且制备方法简单,无需镀多层薄膜,成本低。

实施例2:

本实施例中制备Sn掺杂Ge2Sb2Te5热电薄膜。

本实施例制备过程与实施例1基本相同,不同之处在于Sn掺杂功率设为50W,并调整沉积时间,制备得到Sn0.17(Ge2Sb2Te5)0.83热电薄膜,厚度分别为205nm、388nm;且步骤(4)中,退火温度为210℃,退火时间为25min。

将本实施例制备得到的薄膜进行形貌表征和性能测试,结果同实施例1制备得到的Sn0.17(Ge2Sb2Te5)0.83热电薄膜测试结果相符。

实施例3:

本实施例中制备Sn掺杂Ge2Sb2Te5热电薄膜。

本实施例制备过程与实施例1基本相同,其中,Sn掺杂功率设为50W,制备得到Sn0.17(Ge2Sb2Te5)0.83热电薄膜,厚度为300nm;

不同之处在于:步骤(4)中,退火温度为分别设置为180℃、200℃、250℃、300℃、320℃,退火时间为30min。

将制备得到的五组热电薄膜进行热电性能测试,结果如下表3所示,可以看出退火温度在200~300℃之间的薄膜,热电性能优异;而退火温度180℃和320℃制备得到的薄膜,热电性能较差。

表3

实施例4:

本实施例中制备Sn掺杂Ge2Sb2Te5热电薄膜。

本实施例制备过程与实施例1基本相同,不同之处在于Sn掺杂功率设为60W,制备得到Sn0.25(Ge2Sb2Te5)0.75热电薄膜,厚度为300nm;测试结果如下表4所示。

表4

【EN】

Sn doped Ge2Sb2Te5Thermoelectric film and method for manufacturing the same

Technical Field

The invention relates to a thermoelectric film and a preparation method thereof, in particular to a Sn-doped Ge film2Sb2Te5A thermoelectric film and a method for manufacturing the same.

Background

The appearance of novel energy sources such as solar energy, wind energy, tidal energy and the like relieves the energy shortage and environmental pollution, but is far from enough, and the seeking of more novel energy sources is urgent at present. Since seebeck, a german scientist in the 20 th of the 19 th century, discovered the thermoelectric generation effect, thermoelectric materials as novel energy materials for mutual conversion of heat energy and electric energy rapidly become a new research direction in the field of materials science. In recent decades, with the continuous progress of material science, new semiconductor materials and nanotechnology, scientists worldwide are continuously exploring and developing various new thermoelectric materials with use value. The thermoelectric cell is a green environment-friendly energy source which is widely applicable, and mainly converts heat energy and electric energy directly into each other through the thermoelectric effect of thermoelectric materials, thereby realizing thermoelectric power generation.

At present, thermoelectric conversion materials have been applied to national defense and high and new technology fields, such as aviation aircrafts, medical products, automobile cushions and the like; also in electronics, such as cooling of electronic equipment, electronic devices, computers, etc.; also have applications in industries such as automotive freezers, oil detectors, high vacuum cold traps, etc. However, the thermoelectric conversion efficiency of the thermoelectric materials used in the prior art is generally not high, and the specific power that can be provided is also limited. With the development of micro-nano electronic devices, novel micro-nano electromechanical systems and micro integrated systems, the thermoelectric conversion function of thermoelectric materials is utilized to provide uninterrupted energy for systems with lower power consumption, such as micro-nano integrated circuits and the like, so that the development and research of thermoelectric thin film materials are promoted greatly. Due to the nature of thermoelectric materials, the manufacturing cost is high, the conversion efficiency is low, and the thermoelectric device is difficult to be used on a large scale.

Disclosure of Invention

The purpose of the invention is as follows: it is an object of the present invention to provide a Sn doped Ge2Sb2Te5The thermoelectric film has high thermoelectric conversion efficiency and low cost; another object of the present invention is to provide a Sn-doped Ge2Sb2Te5The preparation method of the thermoelectric film has simple preparation process, and the prepared film has high conversion efficiency and is beneficial to large-scale use of thermoelectric devices.

The technical scheme is as follows: the invention provides Sn doped Ge2Sb2Te5Thermoelectric thin film of Ge2Sb2Te5And Sn as raw material, and adopting a magnetron sputtering codeposition method to deposit and obtain a single-layer Sn doped Ge on the substrate2Sb2Te5A thermoelectric thin film; the chemical formula of the film material is Snx(Ge2Sb2Te5)1-xWherein x is more than 0 and less than 0.25.

Preferably, the thickness of the film is 200-400 nm; sn doped Ge at this thickness2Sb2Te5The thermoelectric performance of the thermoelectric film is optimal.

Ge in the prior art2Sb2Te5Is a chalcogenide phase change memory material with larger electric conduction, small energy band gap and larger effective mass, and the invention breakthroughs in selecting Ge2Sb2Te5Preparing thermoelectric material from the material, doping Sn element, and performing magnetron sputtering codeposition to obtain Sn-doped Ge2Sb2Te5The thermoelectric thin film material has high thermoelectric conversion efficiency and low preparation cost.

The invention also provides Sn doped Ge2Sb2Te5The preparation method of the thermoelectric film specifically comprises the following steps:

(1) in a magnetron sputtering system, a Sn target material is placed at a magnetron radio frequency sputtering target position, and Ge is put at a magnetron radio frequency sputtering target position2Sb2Te5Placing the target material on a magnetic control direct current sputtering target position, and closing the chamber door;

(2) vacuumizing the cavity, and introducing inert gas, wherein the gas flow is set to be 20sccm or below;

(3) deposition of Sn doped Ge on a substrate by sputter co-deposition2Sb2Te5A film;

(4) carrying out vacuum annealing on the film obtained by deposition in a vacuum annealing furnace to obtain the Sn doped Ge in an annealed state2Sb2Te5A thermoelectric thin film.

Wherein, the substrates used for deposition are quartz plates and silicon wafers; the purpose of testing the substrates is different, the silicon wafer can be used for testing the phase structure and the section effect of the doped film, and the quartz plate can be used for testing thermoelectric parameters.

In the step (2), the vacuum degree of the magnetron sputtering background is kept at 1.0 multiplied by 10 in the vacuum-pumping stage-4~4.0×10-4And Pa, then introducing inert gas to set the pressure of the magnetron sputtering system at 0.4-1.0 Pa.

In order to optimize the thermoelectric property of the film, in the step (3), the radio frequency sputtering power of the Sn target material is set to be 20-55W, and Ge is set2Sb2Te5Setting the direct-current sputtering power of the target material to be 50-60W; the sputtering time is 30-45 min; furthermore, the radio frequency sputtering power of the Sn target is set to be 40-55W.

And (4) annealing in vacuum at 200-300 ℃ for 20-30 min.

Specifically, the Sn is doped with Ge2Sb2Te5The preparation method of the thermoelectric film comprises the following steps:

A. selecting Sn target material with the purity of 99.99 percent and Ge with the purity of 99.99 percent2Sb2Te5Using Sn target material and Ge as raw materials2Sb2Te5The targets are respectively arranged on station target racks of the sputtering system;

B. pumping the background vacuum degree of the sputtering system to 1.0-4.0 multiplied by 10-4Pa, introducing inert gas, and controlling the pressure of the sputtering system to be 0.4-1 Pa;

C. deposition of Sn doped Ge on silicon chip and quartz substrate by sputtering codeposition method2Sb2Te5A film;

D. will be depositedCarrying out heat treatment on the film at the temperature of 200-300 ℃ to obtain Sn doped Ge2Sb2Te5A thermoelectric thin film.

The key technical links of the invention are respectively the selection design of materials and the control of preparation process conditions, and the two supplement each other. The measurement of thermoelectric material performance is characterized mainly by a dimensionless ZT, wherein ZT is S2σ T/K, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and K is the thermal conductivity (T is a certain temperature, and ZT values at different temperatures are different). Generally, the thermoelectric figure of merit of a thermoelectric material is an important criterion for determining whether a thermoelectric material can be effectively applied to a thermoelectric device, and a thermoelectric figure of merit of less than 1 of a thermoelectric material is not favorable for the application of the thermoelectric device, and has a low thermoelectric conversion value. And Ge2Sb2Te5The Sn-doped Ge-doped phase-change memory material is a chalcogenide phase-change memory material, has larger electric conduction, small energy band gap and larger effective mass, is applied to thermoelectric thin film materials in a breakthrough manner, is doped with Sn, is successfully prepared by adopting a magnetron sputtering codeposition method and combining with a preferred preparation process2Sb2Te5The thermoelectric thin film material greatly improves the Seebeck coefficient of the material.

Has the advantages that:

(1) the preparation method of the invention is to form the Sn doped Ge with the nano structure by controlling the thickness of the nano layer to perform the layer prefabrication mode2Sb2Te5The content of Sn doping is adjusted by adjusting and controlling the preparation process parameters of the film, so that a complete and compact film with a nano structure is formed, and the thermoelectric performance of the thermoelectric film is greatly improved.

(2) Compared with the prior art, the invention deposits the single layer Sn doped Ge on the substrate through material design and optimized process parameters2Sb2Te5The thermoelectric film greatly improves the thermoelectric conversion efficiency of the material and can effectively reduce the preparation of the nano Sn doped Ge2Sb2Te5The complexity and the cost of the manufacturing process of the film are favorable for popularization and application.

Drawings

FIG. 1 is a view of as-deposited Sn-Ge2Sb2Te5The thermoelectric thin film is formed schematically.

FIG. 2 is an annealed Sn-Ge film2Sb2Te5The thermoelectric thin film is formed schematically.

FIG. 3 is Sn-Ge2Sb2Te5Thermoelectric thin film XRD patterns.

FIG. 4 is Sn-Ge2Sb2Te5Cross-sectional SEM pictures of the thermoelectric thin films.

FIG. 5 is Sn-Ge2Sb2Te5Surface topography SEM pictures of thermoelectric films.

FIG. 6 is Ag-Ge2Sb2Te5XRD pattern of thermoelectric thin film.

FIG. 7 is Ag-Ge2Sb2Te5Surface topography SEM pictures of thermoelectric films.

Detailed Description

The present invention will be described in further detail with reference to examples and comparative examples.

The starting materials and reagents used in the following examples and comparative examples are commercially available.

Example 1:

preparation of Sn doped Ge in this example2Sb2Te5A thermoelectric thin film.

Plating film by adopting a magnetron sputtering mode, and plating Sn and Ge with the purity of 99.99 percent2Sb2Te5The target material is arranged on a sputtering target position of a magnetron sputtering chamber, a silicon wafer and a quartz glass sheet are used as substrates, and a single-layer Sn doped Ge is obtained by deposition on a substrate2Sb2Te5A thermoelectric thin film.

The preparation method specifically comprises the following steps:

(1) selecting Sn target material with the purity of 99.99 percent and Ge with the purity of 99.99 percent2Sb2Te5Using a target material as a raw material, and then using a Sn target material and Ge as raw materials2Sb2Te5The target materials are respectively arranged on a station target material rack of the sputtering system, a chamber door is closed, and an air release valve is closed; namely, placing the Sn target material at a magnetron radio frequency sputtering target position, and placing Ge at the target position2Sb2Te5The target material is placed on a magnetic control direct current sputtering target position.

(2) Vacuumizing, wherein the background vacuum degree of a sputtering system is pumped to 1.0 multiplied by 10-4Pa, introducing argon gas with the flow rate of 20sccm, and controlling the pressure of the sputtering system at 0.4 Pa;

(3) adjusting Ge by adopting a magnetron sputtering codeposition method2Sb2Te5The power of the target is 60W, the power of the Sn target is respectively set to be 20W, 30W, 40W, 50W and 55W, and Sn doped Ge is deposited on a silicon wafer and a quartz substrate2Sb2Te5Depositing the film for 45min to obtain the Sn-doped Ge in the deposition state2Sb2Te5A thermoelectric thin film.

Sn-doped Ge2Sb2Te5The film thickness was about 300nm and the film deposition rate was measured to be about 6.65 nm/min.

(4) Carrying out heat treatment on the co-deposited film, wherein the heat treatment temperature is 280 ℃, the annealing time is 30min, and finally obtaining Sn doped Ge2Sb2Te5A thermoelectric thin film.

This example is implemented by selecting an elemental target Sn target and a compound target Ge2Sb2Te5Target as a starting material, Sn-doped Ge was co-deposited on the substrate 12Sb2Te5A film 2, as shown in FIG. 1; then annealing the thin film as shown in FIG. 2; finally forming Sn doped Ge2Sb2Te5In the thermoelectric thin film 3, Sn was prepared when the Sn target power was 20W0.05(Ge2Sb2Te5)0.95A thermoelectric thin film; when the power of the Sn target is 30W, Sn is prepared0.11(Ge2Sb2Te5)0.89A thermoelectric thin film; when the power of the Sn target is 40W, Sn is prepared0.14(Ge2Sb2Te5)0.86A thermoelectric thin film; when the power of the Sn target is 50W, Sn is prepared0.17(Ge2Sb2Te5)0.83A thermoelectric thin film; when the power of the Sn target is 55W, Sn is prepared0.23(Ge2Sb2Te5)0.77A thermoelectric thin film.

The prepared Sn-Ge is shown in figure 32Sb2Te5Thermoelectric power generationThin film XRD pattern, FIG. 4 is Sn-Ge2Sb2Te5SEM image of the cross section of the thermoelectric film, it can be seen from FIG. 3 that Sn element is doped into Ge2Sb2Te5In the structure, a single-phase solid solution is formed, and FIG. 4 shows Sn-Ge2Sb2Te5Scanning cross-sectional view of the thermoelectric thin film with a cross-sectional thickness of 300nm, and Sn-Ge in FIG. 52Sb2Te5The surface topography of the thermoelectric film has good compactness of the film layer.

As shown in table 1 below, in order to obtain the thermoelectric properties of the prepared thin film, the Sn sputtering powers of 20W, 30W, 40W, 50W and 55W are respectively shown in the table, and the measured temperature is measured under 723k, it can be seen that the seebeck coefficient is increased with the increase of the Sn doping power, the resistivity is reduced, the thermal conductivity is also reduced, and the power factor and the thermoelectric figure of merit are improved.

TABLE 1

Comparative example:

this comparative example prepares Ag doped Ge2Sb2Te5A thermoelectric thin film.

The method specifically comprises the following steps:

(1) selecting an Ag target material with the purity of 99.99 percent and Ge with the purity of 99.99 percent2Sb2Te5Using target material as raw material, then using Ag target material and Ge2Sb2Te5The target materials are respectively arranged on a station target material rack of the sputtering system, a chamber door is closed, and an air release valve is closed;

(2) vacuumizing, wherein the background vacuum degree of a sputtering system is pumped to 1.0 multiplied by 10-4Pa, introducing argon gas with the flow rate of 20sccm, and controlling the pressure of the sputtering system at 0.4 Pa;

(3) adjusting Ge by adopting a magnetron sputtering codeposition method2Sb2Te5The target power is 60W, the Ag target power is respectively set to 6W, 8W, 10W and 12W, and the Ag-doped Ge is deposited on a silicon wafer and a quartz substrate2Sb2Te5Film, depositionThe time is 50min, and the deposited Ag doped Ge is obtained2Sb2Te5A thermoelectric thin film; the thickness of the film was about 280nm, and the deposition rate of the film was 5.6nm/min in terms of conversion.

(4) Carrying out heat treatment on the co-deposited film, wherein the heat treatment temperature is 250 ℃, and the annealing time is 25min, so as to obtain Ag doped Ge2Sb2Te5A thermoelectric thin film.

This example is carried out by selecting an elemental target Ag target and a compound target Ge2Sb2Te5Target as raw material, co-depositing Ag-doped Ge on substrate2Sb2Te5Film of Ag-Ge prepared as shown in FIG. 62Sb2Te5XRD pattern of the thermoelectric film, FIG. 7 is Ag-Ge2Sb2Te5A surface topography map of the thermoelectric film; from FIG. 6, it can be seen that when Ag is doped into Ge2Sb2Te5In the crystal structure, secondary phases are separated out, and the thermoelectric performance of the crystal is influenced; as can be seen from FIG. 7, Ag is doped with Ge2Sb2Te5The quality of the thermoelectric film is poor, the surface defects and cavities are increased, and the surface compactness of the film layer is reduced.

The thermoelectric properties of the prepared film are shown in the following table 2, in which the Ag sputtering power is 6W, 8W, 10W, 12W, and the measured temperature is measured at 723 k; it can be seen that Ag is doped with Ge2Sb2Te5The hot spot figure of merit of the thermoelectric film is significantly lower than that of Sn-doped Ge2Sb2Te5A thermoelectric thin film; moreover, as the doping power continues to increase, the thermoelectric performance thereof decreases.

TABLE 2

It can be seen that the Ag-doped thermoelectric film has poor quality, cannot be used in thermoelectric devices, and has poor thermoelectric performance; whereas the prior art thermoelectric films had a hotspot figure of merit of at most about 0.5-0.7, relative to the thermoelectric films and Ag-doped Ge films commonly used in the prior art2Sb2Te5Thermoelectric thin film, the present invention innovatively employs Sn-doped Ge2Sb2Te5The thermoelectric film obtained by the method can greatly improve the Seebeck coefficient of the material, the thermoelectric performance of the film material is excellent, the preparation method is simple, the multilayer film does not need to be plated, and the cost is low.

Example 2:

preparation of Sn doped Ge in this example2Sb2Te5A thermoelectric thin film.

The process of this example is substantially the same as that of example 1, except that Sn is prepared by adjusting the deposition time with the Sn doping power set at 50W0.17(Ge2Sb2Te5)0.83The thickness of the thermoelectric film is 205nm and 388nm respectively; in the step (4), the annealing temperature is 210 ℃, and the annealing time is 25 min.

The film prepared in this example was subjected to morphology characterization and performance testing, and the results were the same as those of Sn prepared in example 10.17(Ge2Sb2Te5)0.83The thermoelectric film test results are consistent.

Example 3:

preparation of Sn doped Ge in this example2Sb2Te5A thermoelectric thin film.

The preparation process of this example is substantially the same as that of example 1, wherein the doping power of Sn is set to 50W, and Sn is prepared0.17(Ge2Sb2Te5)0.83A thermoelectric thin film with a thickness of 300 nm;

the difference lies in that: in the step (4), the annealing temperatures are respectively set to be 180 ℃, 200 ℃, 250 ℃, 300 ℃ and 320 ℃, and the annealing time is 30 min.

The five groups of prepared thermoelectric films are subjected to thermoelectric performance test, and the results are shown in the following table 3, so that the films with the annealing temperature of 200-300 ℃ have excellent thermoelectric performance; the thin film prepared at the annealing temperature of 180 ℃ and 320 ℃ has poor thermoelectric performance.

TABLE 3

Example 4:

preparation of Sn doped Ge in this example2Sb2Te5A thermoelectric thin film.

The process of this example is substantially the same as that of example 1, except that the doping power of Sn is set to 60W, and Sn is prepared0.25(Ge2Sb2Te5)0.75A thermoelectric thin film with a thickness of 300 nm; the test results are shown in table 4 below.

TABLE 4

图1
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