WO2022165905A1 - 一种含有插层的石墨烯/硅肖特基结光电探测器及制备工艺 - Google Patents

一种含有插层的石墨烯/硅肖特基结光电探测器及制备工艺 Download PDF

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WO2022165905A1
WO2022165905A1 PCT/CN2021/079379 CN2021079379W WO2022165905A1 WO 2022165905 A1 WO2022165905 A1 WO 2022165905A1 CN 2021079379 W CN2021079379 W CN 2021079379W WO 2022165905 A1 WO2022165905 A1 WO 2022165905A1
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silicon
graphene
schottky junction
iron garnet
gadolinium
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PCT/CN2021/079379
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French (fr)
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杨树明
吉培瑞
邓惠文
张泽
索浩
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西安交通大学
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
    • H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the Schottky type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the invention belongs to the technical fields of photoelectric detection, semiconductor physics and micro-nano manufacturing, and particularly relates to a graphene/silicon Schottky junction photodetector containing intercalation and a preparation process.
  • the dark current of the graphene/silicon Schottky junction is exponentially related to the Schottky barrier height, and is also closely related to the contact interface quality.
  • the lower barrier height makes it easy for thermally excited carriers to cross the barrier and form a reverse saturated dark current.
  • the contact interface of graphene/silicon Schottky junction usually has a high density of surface states, resulting in the Fermi level pinning effect, resulting in current-carrying sub-recombination, forming a larger recombination dark current.
  • the literature shows that inserting a thin insulating oxide film at the Schottky junction interface to separate graphene and silicon in space to a certain extent can effectively suppress dark current.
  • Li et al. used the natural oxide layer (silicon dioxide) on the silicon surface as an intercalation layer, and when the thickness was about 2 nm, the dark current was effectively suppressed.
  • the thickness of the intercalation layer is continuously increased, and the thicker oxide layer will block the tunneling of photogenerated carriers and reduce the photoresponse of the device.
  • some researchers have introduced alumina thin films to optimize the Schottky junction interface of graphene/silicon solar cells, but no reports have shown its feasibility on photodetectors.
  • the object of the present invention is to provide a graphene/silicon Schottky junction photodetector containing intercalation for the problems of large dark current and low stability of the graphene/silicon Schottky junction photodetector. and preparation process, effectively suppressing dark current, avoiding the shortcomings of the above-mentioned prior art, and improving the switching ratio, detection rate and stability of the device.
  • the present invention adopts the following technical solutions to be realized:
  • a graphene/silicon Schottky junction photodetector containing intercalation comprising a silicon substrate, a silicon dioxide insulating layer, a back electrode, a gadolinium iron garnet film and a front ring electrode; wherein,
  • the silicon substrate is N-type lightly doped; except for the silicon window area, the silicon substrate is covered by a silicon dioxide insulating layer; the silicon substrate is located in the lower layer of the device, and the back electrode that is in ohmic contact with silicon is arranged below; the graphene is located in the upper layer of the device, A front ring electrode in ohmic contact with graphene is arranged above; the front ring electrode does not exceed the graphene area outside the silicon window; the contact between the graphene and the silicon window forms a Schottky junction; the thickness of the gadolinium iron garnet film is 1-2 nm , located in the middle of the silicon window and graphene (6), as intercalation.
  • a further improvement of the present invention is that the dielectric constant of the gadolinium iron garnet film is >10.
  • a further improvement of the present invention is that the arithmetic mean roughness of the gadolinium iron garnet thin film is ⁇ 0.5 nm.
  • a further improvement of the present invention lies in that the gadolinium iron garnet film does not undergo chemical reaction at a high temperature of 1000° C. and a water-oxygen environment in the atmosphere, and can maintain stability.
  • a preparation process of a graphene/silicon Schottky junction photodetector containing intercalation comprising the following steps:
  • a further improvement of the present invention is that the resistivity of silicon in step 1) is 5-10 ⁇ cm, silicon acts as both a substrate and a photosensitive material, forming a Schottky junction with graphene.
  • step 4 the gadolinium iron garnet target is first prepared according to the two-step solid-phase sintering method
  • gadolinium oxide and iron oxide powder are reclaimed and then ball-milled, dried, and pre-sintered.
  • the pre-sintering temperature is 1100-1150 °C, and the time is 4-5 h; after pre-sintering, continue to grind to fine powder , and perform secondary ball milling, press to form discs, and perform secondary sintering at a sintering temperature of 1300-1350 °C and a time of 9-10 h to obtain a Gadolinium-iron garnet target with high density and uniform composition;
  • a gadolinium iron garnet film with a thickness of 1-2 nm is deposited by magnetron sputtering technology, wherein the background vacuum is 1 ⁇ 10 -5 -2 ⁇ 10 -5 Pa, and the sputtering pressure is 1-2Pa. Equal volumes of oxygen and argon were introduced, the gas flow was 20-30 sccm, and the sputtering power was 50-60 W.
  • step 5 the graphene is prepared by chemical vapor deposition technology.
  • the present invention provides a graphene/silicon Schottky junction photodetector containing intercalation.
  • Graphene is located in the upper layer of the device, silicon is located in the lower layer of the device, and a uniform, continuous and stable 1-2 nm gadolinium iron garnet film is used as the intercalation layer. , the overall formation of a graphene/Gadolinium-iron-garnet film/silicon composite Schottky junction.
  • the barrier height of the graphene/silicon Schottky junction can be increased, thereby increasing the built-in electric field and suppressing the reverse saturated dark current; the gadolinium iron garnet film also With excellent uniformity and continuity, it can passivate the silicon surface, reduce the surface state density, and then reduce the surface recombination dark current. As a result, the detector has a low dark current, and the photogenerated carriers under the illumination condition are effectively separated, thereby improving the switching ratio and detection rate of the device, and can effectively detect long-distance weak radiation signals.
  • the gadolinium iron garnet film has good temperature and chemical stability. After being deposited on the silicon window, it can isolate the air, prevent silicon oxidation, and improve the time and environmental reliability of the device.
  • the invention provides a preparation process of a graphene/silicon Schottky junction photodetector containing intercalation, which has the advantages of simple operation, strong practicability and high reliability, and a simple and stable preparation method is used to obtain a high-performance photodetector, Suitable for actual production.
  • the graphene/silicon Schottky junction photodetector with intercalation proposed in the present invention can effectively suppress the dark current of the device, improve the detection capability of weak light signals, and improve the long-term stability of the device.
  • the method has strong reliability and simple preparation process, which is helpful to break through the technical bottleneck of the graphene/silicon Schottky junction detector in response to weak photon energy.
  • Fig. 1 is the preparation process schematic diagram of graphene/silicon Schottky junction photodetector containing intercalation
  • Figure 2 is the response curve of a graphene/silicon Schottky junction photodetector with intercalation under periodic optical signals.
  • a graphene/silicon Schottky junction photodetector containing intercalation includes a silicon substrate 1, a silicon dioxide insulating layer 2, a back electrode 3, a silicon window 4, a gadolinium iron Garnet film 5, graphene 6 and front ring electrode 7.
  • the silicon substrate 1 is N-type lightly doped; except for the area of the silicon window 4, the silicon substrate 1 is covered by the silicon dioxide insulating layer 2; the silicon substrate 1 is located in the lower layer of the device, and there is a back surface that is in ohmic contact with silicon.
  • Electrode 3; Graphene 6 is located in the upper layer of the device, and the top is provided with a front ring electrode 7 that is in ohmic contact with graphene; the front ring electrode 7 does not exceed the graphene 6 area outside the silicon window 4; Schottky junction; gadolinium iron garnet film 5 is 1-2 thick nm, located in the middle of the silicon window 4 and graphene 6, acts as an intercalation layer to suppress the dark current of the Schottky junction and improve the on-off ratio and detection rate of the graphene/silicon detector.
  • the present invention designs a composite Schottky junction photodetector with an insulating oxide gadolinium iron garnet film as an intercalation layer.
  • the working principle is as follows:
  • the barrier height of the graphene/silicon Schottky junction is increased, thereby suppressing the reverse saturation dark current; at the same time, through the excellent uniformity and continuity
  • the gadolinium iron garnet film 5 passivates the silicon surface, reduces the surface density of states, and then reduces the surface composite dark current; and under the condition of illumination, the larger built-in electric field promotes the rapid and effective separation of photogenerated carriers, and the photocurrent is obtained. promote.
  • the detector has a high switching ratio and detection rate.
  • the gadolinium iron garnet film 5 with good temperature and chemical stability, after being deposited on the silicon window 4 can isolate the air, prevent silicon oxidation, and improve the time and environmental reliability of the device.
  • the present invention provides a preparation process of the intercalated graphene/silicon Schottky junction photodetector. As shown in Figure 1, it includes the following steps:
  • nm Au as the back electrode, forms ohmic contact with silicon
  • the resistivity of silicon in step 1) is 5-10 ⁇ cm, silicon acts as both a substrate and a photosensitive material, forming a Schottky junction with graphene, which has a broad spectrum absorption ability from ultraviolet to near infrared;
  • the gadolinium iron garnet target is first prepared according to the two-step solid-phase sintering method. According to the mass ratio of 3:5, gadolinium oxide and iron oxide powder were taken out and then ball-milled, dried, and pre-sintered. The pre-sintering temperature was 1150 °C and the time was 5 h. After pre-sintering, continue to grind to fine powder, and carry out secondary ball milling. The pellets are pressed into discs with a diameter of 50.1 mm and a thickness of 1 mm for secondary sintering. The sintering temperature is 1350 °C and the time is 10 h. Gadolinium iron garnet target with uniform composition.
  • a gadolinium-iron-garnet film with a thickness of 2 nm was deposited by magnetron sputtering technology, in which the background vacuum was 2 ⁇ 10 -5 Pa, the sputtering pressure was 1 Pa, and equal volumes of oxygen and argon were introduced.
  • the gas flow was 20 sccm, and the sputtering power was set to 60 W.
  • the obtained gadolinium iron garnet film has high uniformity and continuity, and the thickness is precisely controlled.
  • the preparation of gadolinium-iron garnet targets by the above-mentioned two-step solid-phase sintering method can also be implemented according to the following process: according to the mass ratio of 3:5, gadolinium oxide and iron oxide powder are taken and then ball-milled, dried, and pre-sintered, and the pre-sintering temperature to 1100 °C for 4 h. After pre-sintering, continue to grind to fine powder, and then perform secondary ball milling. The pellets are pressed into discs with a diameter of 50.1 mm and a thickness of 2 mm for secondary sintering. The sintering temperature is 1300 °C and the time is 9 h. , Gadolinium iron garnet target with uniform composition.
  • a gadolinium-iron-garnet film with a thickness of 2 nm was deposited by magnetron sputtering technology, in which the background vacuum was 1 ⁇ 10 -5 Pa, the sputtering pressure was 1 Pa, and equal volumes of oxygen and argon were introduced.
  • the gas flow was 30 sccm, and the sputtering power was set to 50 W.
  • the obtained gadolinium iron garnet film has high uniformity and continuity, and the thickness is precisely controlled.
  • step 5 graphene is prepared by chemical vapor deposition technology, which has excellent electrical conductivity and good light transmittance.
  • Graphene is not only used to form a Schottky junction with silicon, but also used as a transparent electrode to promote the transmission of photocurrent in external circuits. .

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Abstract

本发明公开了一种含有插层的石墨烯/硅肖特基结光电探测器及制备工艺。该探测器包括硅基底、二氧化硅、背面电极、硅窗口、钆铁石榴石插层、石墨烯和正面环形电极。利用钆铁石榴石薄膜优异的绝缘性能提高石墨烯/硅肖特基结的势垒高度，进而增大内建电场并抑制反向饱和暗电流；利用钆铁石榴石薄膜优异的均匀性和连续性，钝化硅表面，降低表面态密度，进而减小表面复合暗电流。使得该探测器的暗电流得到抑制，光电流提到提升，进而提高器件的开关比、探测率及可靠性。相应的制备工艺操作简单，稳定性好。本发明有助于突破远距离微弱辐射信号探测的技术瓶颈。

Description

一种含有插层的石墨烯/硅肖特基结光电探测器及制备工艺 技术领域
本发明属于光电探测、半导体物理及微纳制造技术领域，具体涉及一种含有插层的石墨烯/硅肖特基结光电探测器及制备工艺。
 背景技术
当今社会已进入信息化时代，而光电探测技术是现代信息获取的主要手段之一，在自动驾驶、数码成像、光通信等领域具有广泛而迫切的应用需求。石墨烯与硅接触形成的肖特基结是有效的光电探测器件，但通常存在着较大的暗电流。光电探测器的暗电流会降低信噪比，尤其是探测微弱辐射信号时，较大的暗电流将严重干扰到光电流的读取，使得探测器的开关比（光电流与暗电流之比）和探测率降低，限制其走向应用。研究发现，石墨烯/硅肖特基结的暗电流与肖特基势垒高度呈指数关系，也与接触界面质量密切相关。较低的势垒高度使得热激发载流子易越过势垒，形成反向饱和暗电流。由于石墨烯不可避免的悬挂键和硅平面较多的缺陷态，石墨烯/硅肖特基结的接触界面通常具有较高的表面态密度，从而产生费米能级钉扎效应，造成载流子重组，形成较大的重组暗电流。文献表明，在肖特基结界面处插入一层薄的绝缘性氧化薄膜，把石墨烯和硅在空间上一定程度地隔开，可以有效抑制暗电流。Li等人曾利用硅表面的自然氧化层(二氧化硅)作为中间插层，当厚度为2 nm左右时，暗电流得到有效抑制。但由于硅的自然氧化会长期持续，因此插层厚度不断增加，较厚的氧化层会阻挡光生载流子的隧穿，降低器件的光响应。此外，一些研究者引入氧化铝薄膜来优化石墨烯/硅太阳能电池的肖特基结界面，但没有报道表明其在光电探测器上的可行性。最近，Wang等人通过溶液悬涂法在石墨烯/硅肖特基光电探测器中插入了氧化石墨烯纳米片，使暗电流降低了10倍以上。但基于溶液的界面层面临着非均匀涂布和不稳定性问题。因此，石墨烯/硅肖特基结的暗电流较大及稳定性较低的难题始终没有得到较好的解决，寻找均匀稳定的插层材料对构建高性能石墨烯/硅光电探测器有着深远的意义。
 技术问题
本发明的目的在于针对石墨烯/硅肖特基结光电探测器存在的暗电流较大及稳定性较低的问题，提供了一种含有插层的石墨烯/硅肖特基结光电探测器及制备工艺，有效抑制暗电流，并避免上述现有技术所存在的不足之处，提高器件的开关比、探测率及稳定性。
 技术解决方案
为达到上述目的，本发明采用如下技术方案予以实现：
一种含有插层的石墨烯/硅肖特基结光电探测器，包括硅基底、二氧化硅绝缘层、背面电极、钆铁石榴石薄膜和正面环形电极；其中，
硅基底为N型轻掺杂；除硅窗口区域外，硅基底被二氧化硅绝缘层所覆盖；硅基底位于器件下层，下方设置有与硅呈欧姆接触的背面电极；石墨烯位于器件上层，上方设置有与石墨烯呈欧姆接触的正面环形电极；正面环形电极不超出硅窗口以外的石墨烯区域；石墨烯和硅窗口接触形成肖特基结；钆铁石榴石薄膜厚度为1-2 nm，位于硅窗口和石墨烯（6）的中间，作为插层。
本发明进一步的改进在于，钆铁石榴石薄膜的介电常数>10。
本发明进一步的改进在于，钆铁石榴石薄膜的算术平均粗糙度<0.5 nm。
本发明进一步的改进在于，钆铁石榴石薄膜在1000℃高温及大气中水氧环境下不会发生化学反应，能够保持稳定。
一种含有插层的石墨烯/硅肖特基结光电探测器的制备工艺，包括如下步骤：
1）准备清洁的氧化硅片，其中硅为N型轻掺杂，晶向为100，二氧化硅绝缘层的厚度为200-300 nm；
2）使用缓冲氧化物刻蚀液去除氧化硅片背面的天然氧化层，然后通过电子束蒸镀技术在背面沉积Ti和Au，作为背面电极，与硅形成欧姆接触；
3）通过紫外光刻技术在正面定义一个方形区域，并用缓冲氧化物刻蚀液去除该方形区域的二氧化硅绝缘层，露出硅窗口；
4）在硅窗口区域表面沉积一层1-2 nm厚的钆铁石榴石薄膜；
5）将石墨烯转移在钆铁石榴石薄膜上，且石墨烯覆盖的面积大于硅窗口面积；
6）再次使用紫外光刻技术和电子束蒸镀技术在硅窗口以外的石墨烯区域上沉积Ti和Au，作为正面环形电极，与石墨烯形成欧姆接触。
本发明进一步的改进在于，步骤1）中硅的电阻率为5-10 Ω·cm，硅既作为基底，又作为光敏材料，与石墨烯形成肖特基结。
本发明进一步的改进在于，步骤4）中首先按照两步固相烧结法制备钆铁石榴石靶材；
按照质量比为3:5将氧化钆与氧化铁粉末取料后进行球磨、烘干、预烧结，预烧结温度为 1100-1150 ℃，时间为4-5 h；预烧结后继续研磨至细碎粉末，并进行二次球磨，压片制成圆片，进行二次烧结，烧结温度为 1300-1350 ℃，时间 9-10 h，得到致密度较高，成分均匀的钆铁石榴石靶材；利用该靶材，采用磁控溅射技术沉积厚度为1-2 nm的钆铁石榴石薄膜，其中背底真空为1×10 -5-2×10 -5 Pa，溅射气压为1-2Pa，通入等体积的氧气和氩气，气流量为20-30 sccm，溅射功率为于50-60 W。
本发明进一步的改进在于，步骤5）中石墨烯通过化学气相沉积技术制备。
 有益效果
本发明至少具有如下有益的技术效果：
本发明提供的一种含有插层的石墨烯/硅肖特基结光电探测器，石墨烯位于器件上层，硅位于器件下层，均匀连续且稳定的1-2 nm钆铁石榴石薄膜作为插层，整体形成石墨烯/钆铁石榴石薄膜/硅复合肖特基结。由于钆铁石榴石薄膜介电常数高，绝缘性能优异，能够提高石墨烯/硅肖特基结的势垒高度，进而增大内建电场并抑制反向饱和暗电流；钆铁石榴石薄膜还具有优异的均匀性和连续性，能够钝化硅表面，降低表面态密度，进而减小表面复合暗电流。使得该探测器具有较低的暗电流，在光照条件下的光生载流子得到有效分离，进而提高器件的开关比和探测率，能够有效探测远距离微弱辐射信号。并且，钆铁石榴石薄膜具有良好的温度和化学稳定性，沉积在硅窗口上后，可以隔绝空气，防止硅氧化，提高器件的时间和环境可靠性。
本发明提供的一种含有插层的石墨烯/硅肖特基结光电探测器的制备工艺，操作简单、实用性强、可靠性高，采用简单稳定的制备方法得到高性能的光电探测器，适用于实际生产。
综上所述，本发明提出的含有插层的石墨烯/硅肖特基结光电探测器能够有效抑制器件的暗电流，提高微弱光信号的探测能力，提高器件的长期稳定性。方法可靠性强，制备工艺操作简单，有助于突破石墨烯/硅肖特基结探测器在弱光子能量响应的技术瓶颈。
 附图说明
图1是含有插层的石墨烯/硅肖特基结光电探测器的制备工艺示意图；
图2是含有插层的石墨烯/硅肖特基结光电探测器在周期性光信号下的响应曲线。
附图标记说明：
1-硅基底，2-二氧化硅绝缘层，3-背面电极，4-硅窗口，5-钆铁石榴石薄膜，6-石墨烯，7-正面环形电极。
 本发明的最佳实施方式
为使本发明的目的、技术方案及优势更加清楚明了，下面结合附图和实施例对本发明原理及实验过程作进一步说明。
如图1所示，本发明提供的一种含有插层的石墨烯/硅肖特基结光电探测器，包括硅基底1、二氧化硅绝缘层2、背面电极3、硅窗口4、钆铁石榴石薄膜5、石墨烯6和正面环形电极7。其中，硅基底1为N型轻掺杂；除硅窗口4的区域外，硅基底1被二氧化硅绝缘层2所覆盖；硅基底1位于器件下层，下方设置有与硅呈欧姆接触的背面电极3；石墨烯6位于器件上层，上方设置有与石墨烯呈欧姆接触的正面环形电极7；正面环形电极7不超出硅窗口4以外的石墨烯6区域；石墨烯6和硅窗口4接触形成肖特基结；钆铁石榴石薄膜5的厚度为1-2 nm，位于硅窗口4和石墨烯6的中间，作为插层，抑制肖特基结的暗电流，提高石墨烯/硅探测器的开关比和探测率。
为了有效抑制探测器的暗电流，提高器件的开关比和探测率，本发明设计了以绝缘性氧化物钆铁石榴石薄膜为插层的复合肖特基结光电探测器，工作原理为：
通过插入介电常数高，绝缘性能优异的钆铁石榴石薄膜5，提高石墨烯/硅肖特基结的势垒高度，进而抑制反向饱和暗电流；同时，通过均匀性和连续性优异的钆铁石榴石薄膜5，钝化硅表面，降低表面态密度，进而减小表面复合暗电流；并且在光照条件下，更大的内建电场促使光生载流子快速有效的分离，光电流得到提升。整体使得探测器具有高的开关比及探测率。并且，具有良好温度和化学稳定性的钆铁石榴石薄膜5，沉积在硅窗口4上后，可以隔绝空气，防止硅氧化，提高器件的时间和环境可靠性。
为了简单高效实现上述含有插层石墨烯/硅肖特基结光电探测器，本发明提供了一种含有插层的石墨烯/硅肖特基结光电探测器的制备工艺。如图1所示，包括如下步骤：
1）准备清洁的氧化硅片，其中硅为N型轻掺杂，晶向为100，二氧化硅绝缘层的厚度为300 nm；
2）使用缓冲氧化物刻蚀液去除氧化硅片背面的天然氧化层，然后立即通过电子束蒸镀技术在背面沉积20 nm Ti和80 nm Au，作为背面电极，与硅形成欧姆接触；
3）通过紫外光刻技术在正面定义一个1×1 mm的方形区域，并用缓冲氧化物刻蚀液去除该方形区域的二氧化硅绝缘层，露出1×1 mm的硅窗口；
4）在硅窗口区域表面沉积一层1-2 nm厚的钆铁石榴石薄膜；
5）将石墨烯转移在钆铁石榴石薄膜上，且石墨烯覆盖的面积大于硅窗口面积；
6）再次使用紫外光刻技术和电子束蒸镀技术在硅窗口以外的石墨烯区域上沉积20 nm Ti和80 nm Au，作为正面环形电极，与石墨烯形成欧姆接触。其中：
步骤1）中硅的电阻率为5-10 Ω·cm，硅既作为基底，又作为光敏材料，与石墨烯形成肖特基结，具有从紫外-近红外的宽光谱吸收能力；
步骤4）中首先按照两步固相烧结法制备钆铁石榴石靶材。按照质量比为3:5将氧化钆与氧化铁粉末取料后进行球磨、烘干、预烧结，预烧结温度为 1150 ℃，时间 5 h。预烧结后继续研磨至细碎粉末，并进行二次球磨，压片制成直径为 50.1 mm，厚度 1mm的圆片进行二次烧结，烧结温度为 1350℃，时间10 h，得到致密度较高，成分均匀的钆铁石榴石靶材。利用该靶材，采用磁控溅射技术沉积厚度为2 nm的钆铁石榴石薄膜，其中背底真空为2×10 -5 Pa，溅射气压为1 Pa，通入等体积的氧气和氩气，气流量均为20 sccm，溅射功率设置为60 W。得到的钆铁石榴石薄膜具有较高的均匀性和连续性，厚度控制精准。
上述两步固相烧结法制备钆铁石榴石靶材还可以按如下工艺实施：按照质量比为3:5将氧化钆与氧化铁粉末取料后进行球磨、烘干、预烧结，预烧结温度为 1100 ℃，时间 4 h。预烧结后继续研磨至细碎粉末，并进行二次球磨，压片制成直径为 50.1 mm，厚度 2 mm的圆片进行二次烧结，烧结温度为 1300 ℃，时间9 h，得到致密度较高，成分均匀的钆铁石榴石靶材。利用该靶材，采用磁控溅射技术沉积厚度为2 nm的钆铁石榴石薄膜，其中背底真空为1×10 -5 Pa，溅射气压为1 Pa，通入等体积的氧气和氩气，气流量均为30 sccm，溅射功率设置为50 W。得到的钆铁石榴石薄膜具有较高的均匀性和连续性，厚度控制精准。
步骤5）中石墨烯通过化学气相沉积技术制备，导电性能优异，光透过性好，石墨烯既用来与硅形成肖特基结，又用作透明电极，促进光电流在外电路中的传输。
为了验证上述理论及系统的可行性，测试了含有插层与不含插层的探测器在周期性光信号下的响应曲线，如图2所示。对比两者测量结果可知，含有插层的光电探测器暗电流得到抑制，光电流得到提升，进而开关比和探测率增强。
以上结合附图对本发明的具体实施方法作了说明，但这些说明不能被理解为限制了本发明的范围，本发明的保护范围由随附的权利要求书限定，任何在本发明权利要求基础上的改动都是本发明的保护范围。

Claims (8)

  1. 一种含有插层的石墨烯/硅肖特基结光电探测器，其特征在于，包括硅基底（1）、二氧化硅绝缘层（2）、背面电极（3）、钆铁石榴石薄膜（5）和正面环形电极（7）；其中，
    硅基底（1）为N型轻掺杂；除硅窗口（4）区域外，硅基底（1）被二氧化硅绝缘层（2）所覆盖；硅基底（1）位于器件下层，下方设置有与硅呈欧姆接触的背面电极（3）；石墨烯（6）位于器件上层，上方设置有与石墨烯呈欧姆接触的正面环形电极（7）；正面环形电极（7）不超出硅窗口（4）以外的石墨烯（6）区域；石墨烯（6）和硅窗口（4）接触形成肖特基结；钆铁石榴石薄膜（5）厚度为1-2 nm，位于硅窗口（4）和石墨烯（6）的中间，作为插层。
  2. 根据权利要求1所述的一种含有插层的石墨烯/硅肖特基结光电探测器，其特征在于，钆铁石榴石薄膜（5）的介电常数>10。
  3. 根据权利要求1所述的一种含有插层的石墨烯/硅肖特基结光电探测器，其特征在于，钆铁石榴石薄膜（5）的算术平均粗糙度<0.5 nm。
  4. 根据权利要求1所述的一种含有插层的石墨烯/硅肖特基结光电探测器，其特征在于，钆铁石榴石薄膜在1000℃高温及大气中水氧环境下不会发生化学反应，能够保持稳定。
  5. 一种含有插层的石墨烯/硅肖特基结光电探测器的制备工艺，包括如下步骤：
    步骤1，准备清洁的氧化硅片，其中硅为N型轻掺杂，晶向为100，二氧化硅绝缘层的厚度为200-300 nm；
    步骤2，使用缓冲氧化物刻蚀液去除氧化硅片背面的天然氧化层，然后通过电子束蒸镀技术在背面沉积Ti和Au，作为背面电极，与硅形成欧姆接触；
    步骤3，通过紫外光刻技术在正面定义一个方形区域，并用缓冲氧化物刻蚀液去除该方形区域的二氧化硅绝缘层，露出硅窗口；
    步骤4，在硅窗口区域表面沉积一层1-2 nm厚的钆铁石榴石薄膜；
    步骤5，将石墨烯转移在钆铁石榴石薄膜上，且石墨烯覆盖的面积大于硅窗口面积；
    步骤6，再次使用紫外光刻技术和电子束蒸镀技术在硅窗口以外的石墨烯区域上沉积Ti和Au，作为正面环形电极，与石墨烯形成欧姆接触。
  6. 根据权利要求5所述的一种含有插层的石墨烯/硅肖特基结光电探测器的制备工艺，其特征在于，步骤1）中硅的电阻率为5-10 Ω·cm，硅既作为基底，又作为光敏材料，与石墨烯形成肖特基结。
  7. 根据权利要求5所述的一种含有插层的石墨烯/硅肖特基结光电探测器的制备工艺，其特征在于，步骤4）中首先按照两步固相烧结法制备钆铁石榴石靶材；
    按照质量比为3:5将氧化钆与氧化铁粉末取料后进行球磨、烘干、预烧结，预烧结温度为 1100-1150 ℃，时间为4-5 h；预烧结后继续研磨至细碎粉末，并进行二次球磨，压片制成圆片，进行二次烧结，烧结温度为 1300-1350 ℃，时间 9-10 h，得到致密度较高，成分均匀的钆铁石榴石靶材；利用该靶材，采用磁控溅射技术沉积厚度为1-2 nm的钆铁石榴石薄膜，其中背底真空为1×10 -5-2×10 -5 Pa，溅射气压为1-2Pa，通入等体积的氧气和氩气，气流量为20-30 sccm，溅射功率为于50-60 W。
  8. 根据权利要求5所述的一种含有插层的石墨烯/硅肖特基结光电探测器的制备工艺，其特征在于，步骤5）中石墨烯通过化学气相沉积技术制备。
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