CN116936670A - A high-speed germanium-silicon photodetector - Google Patents

A high-speed germanium-silicon photodetector Download PDF

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CN116936670A
CN116936670A CN202311116318.1A CN202311116318A CN116936670A CN 116936670 A CN116936670 A CN 116936670A CN 202311116318 A CN202311116318 A CN 202311116318A CN 116936670 A CN116936670 A CN 116936670A
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germanium
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absorption region
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余宇
石洋
邹明洁
李祖航
张新亮
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Huazhong University of Science and Technology
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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10FINORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/20Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
    • H10F30/21Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
    • H10F30/22Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes
    • H10F30/223Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes the potential barrier being a PIN barrier
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10FINORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10FINORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00Constructional details of devices covered by this subclass
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Abstract

The invention discloses a high-speed germanium-silicon photoelectric detector. The high-speed germanium-silicon photoelectric detector comprises: the device comprises a doped silicon layer, a germanium absorption region, a doped germanium layer, a contact electrode and a germanium upper electrode; the doping polarity of the doped silicon layer is opposite to that of the doped germanium layer, and the doped silicon layer, the germanium absorption region and the doped germanium layer are sequentially connected into a vertical PIN junction; the contact electrodes are arranged on the doped silicon layer, the contact electrodes surround three sides of the germanium absorption region, and the germanium upper electrode is arranged on the doped germanium layer; the contact electrode and the germanium upper electrode collect photo-generated carriers generated by light absorption of the germanium absorption region to form photocurrent; the distance between each side of the contact electrode and the corresponding side in the germanium absorbing region is inversely proportional to the side length of the germanium absorbing region. The technical problem that parasitic capacitance and parasitic resistance are mutually restricted when the RC parasitic effect is reduced by reducing the resistance and is used for improving the bandwidth of the detector is solved.

Description

一种高速锗硅光电探测器A high-speed germanium-silicon photodetector

技术领域Technical field

本发明属于光电探测器技术领域,更具体地,涉及一种高速锗硅光电探测器。The invention belongs to the technical field of photoelectric detectors, and more specifically, relates to a high-speed silicon germanium photodetector.

背景技术Background technique

硅基光子技术兼容CMOS工艺,具备工艺成熟和高集成度的优势,能满足光电子器件的集成化、低成本的需求。在硅基光子技术中,硅基锗光电探测器是实现光电转换的核心器件。随着全球通信容量的快速增长,对探测器的带宽的提升与日俱增。然而,探测器的带宽受限于RC寄生效应,也就是寄生电容和寄生电阻的影响,难以支持高速的光电探测。探测器的寄生电容与锗的面积成正比。探测器的寄生电阻包括两部分,分别为金属与硅的接触电阻和掺杂硅层的电阻,其中掺杂硅层的电阻又是整体的寄生电阻的主要成分。主流的探测器采用与锗吸收区平行的掺杂硅上电极,这时掺杂硅层的电阻与锗的面积成反比,寄生电容和电阻是一对矛盾量,其乘积随锗吸收区的尺寸变化较小。Silicon-based photonic technology is compatible with CMOS technology, has the advantages of mature technology and high integration, and can meet the needs of integrated and low-cost optoelectronic devices. In silicon-based photonic technology, silicon-based germanium photodetectors are the core devices for photoelectric conversion. With the rapid growth of global communication capacity, the bandwidth of detectors is increasing day by day. However, the bandwidth of the detector is limited by RC parasitic effects, that is, the influence of parasitic capacitance and parasitic resistance, making it difficult to support high-speed photoelectric detection. The detector's parasitic capacitance is proportional to the germanium area. The parasitic resistance of the detector consists of two parts, namely the contact resistance between metal and silicon and the resistance of the doped silicon layer. The resistance of the doped silicon layer is the main component of the overall parasitic resistance. The mainstream detector uses a doped silicon upper electrode parallel to the germanium absorption area. At this time, the resistance of the doped silicon layer is inversely proportional to the area of germanium. The parasitic capacitance and resistance are a pair of contradictory quantities, and their product increases with the size of the germanium absorption area. The changes are minor.

非专利文献1(Optics express,2011,19(25):24897-24904)报道了一种典型的高速锗硅光电探测器的实现方法,即在SOI基底上外延生长锗吸收区实现垂直型的PIN二极管。图1为非专利文献1中光电探测器的结构示意图,包含P型掺杂硅层101、本征的锗吸收区102、N型掺杂锗层103、硅上平行接触电极104和锗上电极105。其中,101、102和103形成垂直的PIN结。104和105为收集光电流的电极。非专利文献1利用减小锗吸收区的长度的方式来减小寄生电容,从而提升了带宽。但是主要缺陷是减小锗长度的方式使寄生电阻增加,所以带宽的提升十分有限。非专利文献1还证明增加锗吸收区的长度可以减小掺杂硅层的电阻,但是寄生电容更快地增加,不能降低RC寄生效应。Non-patent document 1 (Optics express, 2011, 19(25): 24897-24904) reports a typical implementation method of high-speed silicon germanium photodetector, which is to epitaxially grow a germanium absorption region on an SOI substrate to realize a vertical PIN diode. Figure 1 is a schematic structural diagram of the photodetector in Non-Patent Document 1, including a P-type doped silicon layer 101, an intrinsic germanium absorption region 102, an N-type doped germanium layer 103, a parallel contact electrode 104 on silicon and a germanium upper electrode. 105. Among them, 101, 102 and 103 form a vertical PIN junction. 104 and 105 are electrodes for collecting photocurrent. Non-patent document 1 reduces the parasitic capacitance by reducing the length of the germanium absorption region, thereby increasing the bandwidth. However, the main drawback is that reducing the length of germanium increases the parasitic resistance, so the bandwidth improvement is very limited. Non-patent document 1 also proves that increasing the length of the germanium absorption region can reduce the resistance of the doped silicon layer, but the parasitic capacitance increases faster and cannot reduce the RC parasitic effect.

为了解决上述方案的缺点,非专利文献2(Chinese Optics Letters,2017,15(10):100401)提出保持锗吸收区体积不变,转而减小寄生电阻的方案。该文献公开了一种通过增加平行电极面积来减小金属与硅的接触电阻的方法,但是该方法对掺杂硅层的电阻不起作用,因此对寄生电阻的调控效果很微弱。In order to solve the shortcomings of the above solution, Non-patent Document 2 (Chinese Optics Letters, 2017, 15(10):100401) proposed a solution to keep the volume of the germanium absorption region unchanged and instead reduce the parasitic resistance. This document discloses a method to reduce the contact resistance between metal and silicon by increasing the area of parallel electrodes. However, this method has no effect on the resistance of the doped silicon layer, so the control effect on the parasitic resistance is very weak.

为了解决掺杂硅层的寄生电阻的问题,专利文献3(CN110957354A)报道了一种利用重掺杂硅层来降低电阻率,从而降低掺杂硅层电阻的方法。该方法虽然能够降低寄生电阻,但是不能无限制地降低电阻率,所以仍然亟需新的降低寄生电阻的机制。In order to solve the problem of parasitic resistance of the doped silicon layer, Patent Document 3 (CN110957354A) reports a method of using a heavily doped silicon layer to reduce the resistivity, thereby reducing the resistance of the doped silicon layer. Although this method can reduce parasitic resistance, it cannot reduce resistivity without limit, so a new mechanism for reducing parasitic resistance is still urgently needed.

现有技术的方案中,存在通过降低电阻进而降低RC寄生效应,用以提升探测器带宽时,寄生电容和寄生电阻相互制约的技术问题。In the existing technical solution, there is a technical problem that parasitic capacitance and parasitic resistance mutually restrict each other when reducing the resistance and thereby reducing the RC parasitic effect to increase the detector bandwidth.

发明内容Contents of the invention

针对相关技术的缺陷,本发明的目的在于提供一种高速锗硅光电探测器,旨在解决提升探测器带宽时,寄生电容和寄生电阻相互制约的技术问题。In view of the shortcomings of related technologies, the purpose of the present invention is to provide a high-speed germanium-silicon photodetector, aiming to solve the technical problem of parasitic capacitance and parasitic resistance mutually restricting each other when increasing the detector bandwidth.

为实现上述目的,本发明提供了一种高速锗硅光电探测器,包括:掺杂硅层、锗吸收区、掺杂锗层、接触电极和锗上电极;In order to achieve the above object, the present invention provides a high-speed silicon germanium photodetector, including: a doped silicon layer, a germanium absorption region, a doped germanium layer, a contact electrode and a germanium upper electrode;

所述掺杂硅层与所述掺杂锗层的掺杂极性相反,所述掺杂硅层、锗吸收区和掺杂锗层依次连接成垂直PIN结;The doped silicon layer and the doped germanium layer have opposite doping polarities, and the doped silicon layer, the germanium absorption region and the doped germanium layer are sequentially connected to form a vertical PIN junction;

所述接触电极设置在所述掺杂硅层上,所述接触电极围绕在所述锗吸收区的三个侧面,所述锗上电极设置在所述掺杂锗层上;所述接触电极和所述锗上电极收集所述锗吸收区吸收光而产生的光生载流子,形成光电流;The contact electrode is disposed on the doped silicon layer, the contact electrode surrounds three sides of the germanium absorption region, the germanium upper electrode is disposed on the doped germanium layer; the contact electrode and The germanium upper electrode collects photogenerated carriers generated by absorbing light in the germanium absorption region to form a photocurrent;

所述接触电极的各边与锗吸收区中对应的边之间的距离和锗吸收区的边长成反比。The distance between each side of the contact electrode and the corresponding side in the germanium absorption region is inversely proportional to the side length of the germanium absorption region.

可选的,所述锗吸收区未被所述接触电极围绕的另外一个侧面为光进入所述锗吸收区的通道。Optionally, the other side of the germanium absorption region that is not surrounded by the contact electrode is a channel for light to enter the germanium absorption region.

可选的,所述接触电极为U型金属接触电极。Optionally, the contact electrode is a U-shaped metal contact electrode.

可选的,所述接触电极为未封口的方框型电极。Optionally, the contact electrode is an unsealed square electrode.

可选的,所述掺杂硅层为P型重掺杂,量级为1020cm-3Optionally, the doped silicon layer is P-type heavily doped, with an order of magnitude of 10 20 cm -3 .

可选的,所述掺杂锗层为N型重掺杂,量级为1020cm-3Optionally, the doped germanium layer is N-type heavily doped, with an order of magnitude of 10 20 cm -3 .

可选的,所述掺杂硅层作为光波导,导引入射光进入所述锗吸收区。Optionally, the doped silicon layer acts as an optical waveguide to guide incident light into the germanium absorption region.

通过本发明所构思的以上技术方案,与现有技术相比,能够取得以下有益效果:Through the above technical solutions conceived by the present invention, compared with the existing technology, the following beneficial effects can be achieved:

1、本发明提供了一种高速锗硅光电探测器,利用调控光电流收集路径来降低寄生电阻进而提高探测器带宽的策略,通过增加了一个金属接触结构,形成围绕在锗吸收区的三个侧面的接触电极,在增加光电流收集路径的同时能显著降低掺杂硅层的寄生电阻,且不会额外增加寄生电容,能够有效提高探测器的带宽,增强光探测的速度。1. The present invention provides a high-speed germanium-silicon photodetector, which uses a strategy of regulating the photocurrent collection path to reduce parasitic resistance and thereby increase the detector bandwidth. By adding a metal contact structure, three structures surrounding the germanium absorption area are formed. The contact electrode on the side can significantly reduce the parasitic resistance of the doped silicon layer while increasing the photocurrent collection path without increasing the parasitic capacitance. It can effectively increase the bandwidth of the detector and enhance the speed of light detection.

2、本发明提供了一种高速锗硅光电探测器,增加的金属接触结构兼容原本锗吸收区的设计,在提高了探测器的带宽的同时,不会影响探测器的响应度和暗电流等其他性能,兼容CMOS工艺,可以降低工艺复杂度和生产成本。2. The present invention provides a high-speed germanium-silicon photodetector. The added metal contact structure is compatible with the original design of the germanium absorption area. While improving the bandwidth of the detector, it will not affect the responsivity and dark current of the detector. Other properties are compatible with CMOS technology, which can reduce process complexity and production costs.

附图说明Description of the drawings

图1是现有技术中光电探测器结构示意图;Figure 1 is a schematic structural diagram of a photodetector in the prior art;

图2是本发明实施例提供的一种高速锗硅光电探测器的示意图;Figure 2 is a schematic diagram of a high-speed silicon germanium photodetector provided by an embodiment of the present invention;

图3是本发明实施例提供的一种高速锗硅光电探测器的寄生电阻的原理图;Figure 3 is a schematic diagram of the parasitic resistance of a high-speed germanium-silicon photodetector provided by an embodiment of the present invention;

图4是U型金属接触电极和传统平行电极下的寄生电阻随锗长度变化的曲线图;Figure 4 is a graph showing the variation of parasitic resistance with germanium length under U-shaped metal contact electrodes and traditional parallel electrodes;

图5是基于U型金属接触电极和传统平行电极的硅基锗探测器的频率响应的曲线图;Figure 5 is a graph of the frequency response of a silicon-based germanium detector based on U-shaped metal contact electrodes and traditional parallel electrodes;

图6是本发明实施例提供的另一种高速锗硅光电探测器的示意图。FIG. 6 is a schematic diagram of another high-speed germanium-silicon photodetector provided by an embodiment of the present invention.

具体实施方式Detailed ways

为了使本发明的目的、技术方案及优点更加清楚明白,以下结合附图及实施例,对本发明进行进一步详细说明。应当理解,此处所描述的具体实施例仅仅用以解释本发明,并不用于限定本发明。此外,下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

下面结合一个优选实施例,对上述实施例中涉及的内容进行说明。The content involved in the above embodiment will be described below with reference to a preferred embodiment.

图1为现有技术中的一种光电探测器的结构示意图,如图1所示,该光电探测器100包含P型掺杂硅层101、本征的锗吸收区102、N型掺杂锗层103、硅上平行接触电极104和掺杂锗层上电极105。其中,含P型掺杂硅层101、本征的锗吸收区102和N型掺杂锗层103形成垂直的PIN结,硅上平行接触电极104和锗上电极105为收集光电流的电极。在现有技术中可以利用减小锗吸收区的长度的方式来减小寄生电容,从而提升了带宽,但是减小锗长度的方式使寄生电阻增加,所以带宽的提升十分有限。该方案还证明增加锗吸收区的长度可以减小掺杂硅层的电阻,但是寄生电容随之增加,不能有效地降低RC寄生效应。Figure 1 is a schematic structural diagram of a photodetector in the prior art. As shown in Figure 1, the photodetector 100 includes a P-type doped silicon layer 101, an intrinsic germanium absorption region 102, and N-type doped germanium. layer 103, a parallel contact electrode 104 on the silicon and an electrode 105 on the doped germanium layer. Among them, the P-type doped silicon layer 101, the intrinsic germanium absorption region 102 and the N-type doped germanium layer 103 form a vertical PIN junction. The parallel contact electrode 104 on the silicon and the upper germanium electrode 105 are electrodes for collecting photocurrent. In the prior art, the parasitic capacitance can be reduced by reducing the length of the germanium absorption region, thereby increasing the bandwidth. However, reducing the germanium length increases the parasitic resistance, so the bandwidth improvement is very limited. This solution also proves that increasing the length of the germanium absorption region can reduce the resistance of the doped silicon layer, but the parasitic capacitance increases accordingly and cannot effectively reduce the RC parasitic effect.

如图2所示,一种高速锗硅光电探测器200,包括:掺杂硅层201、锗吸收区202、掺杂锗层203、接触电极204和锗上电极205;As shown in Figure 2, a high-speed silicon germanium photodetector 200 includes: a doped silicon layer 201, a germanium absorption region 202, a doped germanium layer 203, a contact electrode 204 and a germanium upper electrode 205;

所述掺杂硅层201与所述掺杂锗层202的掺杂极性相反,所述掺杂硅层201、锗吸收区202和掺杂锗层203依次连接成垂直PIN结;The doped silicon layer 201 and the doped germanium layer 202 have opposite doping polarities, and the doped silicon layer 201, the germanium absorption region 202 and the doped germanium layer 203 are sequentially connected to form a vertical PIN junction;

所述接触电极204设置在所述掺杂硅层201上,所述接触电极204围绕在所述锗吸收区202的三个侧面,所述锗上电极205设置在所述掺杂锗层203上;所述接触电极204和所述锗上电极205收集所述锗吸收区202吸收光而产生的光生载流子,形成光电流;The contact electrode 204 is disposed on the doped silicon layer 201 , the contact electrode 204 surrounds three sides of the germanium absorption region 202 , and the germanium upper electrode 205 is disposed on the doped germanium layer 203 ; The contact electrode 204 and the germanium upper electrode 205 collect photogenerated carriers generated by absorbing light in the germanium absorption region 202 to form a photocurrent;

所述接触电极的各边与锗吸收区中对应的边之间的距离和锗吸收区的边长成反比。The distance between each side of the contact electrode and the corresponding side in the germanium absorption region is inversely proportional to the side length of the germanium absorption region.

可选的,所述锗吸收区202未被所述接触电极204围绕的另外一个侧面为光进入所述锗吸收区202的通道。Optionally, the other side of the germanium absorption region 202 that is not surrounded by the contact electrode 204 is a channel for light to enter the germanium absorption region 202 .

在本实施例中,所述接触电极204为U型金属接触电极。In this embodiment, the contact electrode 204 is a U-shaped metal contact electrode.

本实施例中,掺杂锗层203上的锗上电极205和掺杂硅层201上的U型金属接触电极204共同构成收集光电流的电极,探测器其他部分由掺杂硅层201、锗吸收区202和掺杂锗层203形成PIN二极管。其中,掺杂硅层201作为光波导,导引入射光进入锗吸收区202;锗吸收区202吸收入射光,从而产生光生载流子;锗上电极205和U型金属接触电极204分别与掺杂锗层203和掺杂硅层201形成欧姆接触,收集光生载流子,形成光电流。掺杂硅层201与掺杂锗层202的掺杂极性相反,在本实施例中,掺杂硅层201为P型重掺杂,掺杂锗层202为N型重掺杂。通过U型金属接触,相较于现有技术方案中的平行接触电极,建立了额外的光电流收集路径,该方案没有改变锗吸收区结构,相当于在不增加PIN结寄生电容的情况下增加了一个新的并联电阻,从而使掺杂硅层201区域的总电阻减小。如图3所示,传统的平行电极有左右两条电流收集路径,等效为两个并联的大小相等的电阻,分别为电阻1和电阻2。更确切地说,锗吸收区边长与电极之间的矩形的掺杂硅层的电阻就是电阻1和电阻2。本实施例中的U型金属接触电极的额外一条边相当于引入了新的并联电阻3。在增加光电流收集路径的同时降低掺杂硅层201的总寄生电阻,在不增加寄生电容的情况下等效的减小了探测器的RC时间常数,从而使得探测器的带宽提高。矩形的掺杂硅层的电阻与电极/锗的距离成正比,与锗的边长成反比。当U型接触电极各边与锗吸收区各边之间的距离并不相等,而是与锗吸收区的边长成反比时,通过简单的数学推理可以发现电阻1~3相等,理论上总电阻变为了原来的1/3。注意到该方法无需改变锗的面积,因而寄生电容不会增加。In this embodiment, the upper germanium electrode 205 on the doped germanium layer 203 and the U-shaped metal contact electrode 204 on the doped silicon layer 201 together constitute an electrode for collecting photocurrent. The other parts of the detector are composed of the doped silicon layer 201, germanium The absorption region 202 and the doped germanium layer 203 form a PIN diode. Among them, the doped silicon layer 201 serves as an optical waveguide, guiding incident light into the germanium absorption region 202; the germanium absorption region 202 absorbs the incident light, thereby generating photogenerated carriers; the germanium upper electrode 205 and the U-shaped metal contact electrode 204 are respectively connected with the doped silicon layer 201. The mixed germanium layer 203 and the doped silicon layer 201 form ohmic contact, collect photogenerated carriers, and form a photocurrent. The doping polarities of the doped silicon layer 201 and the doped germanium layer 202 are opposite. In this embodiment, the doped silicon layer 201 is heavily doped P-type, and the doped germanium layer 202 is heavily doped N-type. Through the U-shaped metal contact, compared with the parallel contact electrodes in the existing technical solution, an additional photocurrent collection path is established. This solution does not change the structure of the germanium absorption region, which is equivalent to increasing the parasitic capacitance of the PIN junction without increasing the A new parallel resistor is added, thereby reducing the total resistance of the doped silicon layer 201 region. As shown in Figure 3, the traditional parallel electrode has two current collection paths on the left and right, which are equivalent to two parallel resistors of equal size, namely resistor 1 and resistor 2. More precisely, the resistance of the rectangular doped silicon layer between the side length of the germanium absorption region and the electrode is resistance 1 and resistance 2. The extra side of the U-shaped metal contact electrode in this embodiment is equivalent to introducing a new parallel resistor 3 . While increasing the photocurrent collection path, the total parasitic resistance of the doped silicon layer 201 is reduced, which effectively reduces the RC time constant of the detector without increasing the parasitic capacitance, thereby increasing the bandwidth of the detector. The resistance of a rectangular doped silicon layer is directly proportional to the electrode/germanium distance and inversely proportional to the side length of the germanium. When the distance between each side of the U-shaped contact electrode and each side of the germanium absorption area is not equal, but is inversely proportional to the side length of the germanium absorption area, it can be found through simple mathematical reasoning that the resistances 1 to 3 are equal, and theoretically the total The resistance becomes 1/3 of the original value. Note that this method does not require changing the germanium area, so the parasitic capacitance does not increase.

根据上述实施例提供的一种高速锗硅光电探测器,仿真得到的U型金属接触电极和传统的平行金属接触电极的寄生电阻随着锗吸收区长度的变化关系如图4所示。在这两种结构下,寄生电阻都随锗长度的增加而减小,但是U型金属接触电极的寄生电阻比平行接触电极的寄生电阻减小了30-50%。假设锗吸收区所在区域中的锗长度未8微米,平行接触电极和U型金属接触电极对应的寄生电阻由48降至28Ω,下降比例为40.6%。如果采用传统的平行接触电极,探测器要达到相同的寄生电阻降低的效果,锗长度需要从8增加到14微米,将导致寄生电容增加75%。According to the high-speed silicon germanium photodetector provided in the above embodiment, the simulated parasitic resistance of the U-shaped metal contact electrode and the traditional parallel metal contact electrode changes with the length of the germanium absorption region as shown in Figure 4. In both structures, the parasitic resistance decreases as the germanium length increases, but the parasitic resistance of the U-shaped metal contact electrode is reduced by 30-50% compared to the parasitic resistance of the parallel contact electrode. Assuming that the germanium length in the area where the germanium absorption zone is located is less than 8 microns, the parasitic resistance corresponding to the parallel contact electrode and the U-shaped metal contact electrode is reduced from 48 to 28Ω, with a reduction ratio of 40.6%. If traditional parallel contact electrodes are used, to achieve the same parasitic resistance reduction effect in the detector, the germanium length needs to be increased from 8 to 14 microns, which will result in a 75% increase in parasitic capacitance.

根据以上两种结构,实际制作两个探测器,分别具有上述两种不同的接触电极。测量两个探测器的频率响应,如图5所示。在-1V的偏置电压下,具有U型金属接触电极的探测器相比于具有平行接触电极的探测器,带宽从83GHz提升到103GHz,因此,可以通过简单的结构改变实现增加光电流的收集路径,减小寄生电阻从而提升带宽的效果,实现103GHz带宽超高速的锗硅光电探测器。并且,由于兼容原本的锗吸收区的设计,不会影响探测器的响应度和暗电流,并且结构简单,兼容CMOS工艺。Based on the above two structures, two detectors are actually produced, each with the above two different contact electrodes. The frequency response of the two detectors was measured as shown in Figure 5. At a bias voltage of -1V, the bandwidth of the detector with U-shaped metal contact electrodes is increased from 83GHz to 103GHz compared with the detector with parallel contact electrodes. Therefore, increased photocurrent collection can be achieved through simple structural changes. path, reducing the parasitic resistance to increase the bandwidth, and realizing an ultra-high-speed silicon germanium photodetector with a bandwidth of 103GHz. Moreover, because it is compatible with the original design of the germanium absorption region, it will not affect the responsivity and dark current of the detector. It has a simple structure and is compatible with CMOS processes.

本发明实施例利用调控光电流收集路径来降低寄生电阻进而提高探测器带宽的策略,增加了一个金属接触结构,形成围绕在锗吸收区的三个侧面的环绕接触电极,在增加光电流收集路径的同时能显著降低掺杂硅层的寄生电阻,解决了通过降低电阻进而降低RC寄生效应,用以提升探测器带宽时,寄生电阻和寄生电容相互制约的技术问题,实现了有效提高探测器的带宽,增强光探测的速度。The embodiment of the present invention utilizes the strategy of regulating the photocurrent collection path to reduce parasitic resistance and thereby increase the detector bandwidth. A metal contact structure is added to form surrounding contact electrodes surrounding the three sides of the germanium absorption region, and the photocurrent collection path is increased. At the same time, it can significantly reduce the parasitic resistance of the doped silicon layer, solving the technical problem of mutual restriction between parasitic resistance and parasitic capacitance when reducing the resistance and thereby reducing the RC parasitic effect to increase the detector bandwidth, thus effectively improving the detector's performance. bandwidth, enhancing the speed of light detection.

在上述实施例的基础上,可选的,所述环绕接触电极为未封口的方框型电极,光从缺口处进入所述锗吸收区的通道。Based on the above embodiment, optionally, the surrounding contact electrode is an unsealed square frame electrode, and light enters the channel of the germanium absorption region from the gap.

如图6所示,本发明的另一个实施例中环绕接触电极采用方框型电极401。本实施例中,虽然方框型电极401的电极形状和上述实施例中的U型金属接触电极不完全一致,但是都是通过增加光电流收集路径以及引入的并联电阻来降低寄生电阻,原理与上述实施例相同,通过4个电阻的并联来实现寄生电阻的减小,402为锗吸收区对应区域。As shown in FIG. 6 , in another embodiment of the present invention, a square-shaped electrode 401 is used to surround the contact electrode. In this embodiment, although the electrode shape of the square electrode 401 is not completely consistent with the U-shaped metal contact electrode in the above embodiment, the parasitic resistance is reduced by increasing the photocurrent collection path and introducing parallel resistance. The principle is the same as that of the U-shaped metal contact electrode in the above embodiment. The same as in the above embodiment, the parasitic resistance is reduced by connecting four resistors in parallel, and 402 is the area corresponding to the germanium absorption area.

进一步的,在符合尺寸要求的情况下,所述环绕接触电极可以采用其他任意形状电极,例如圆弧形,均可实现本发明的有益效果。Furthermore, as long as the size requirements are met, the surrounding contact electrode can be an electrode of any other shape, such as an arc shape, all of which can achieve the beneficial effects of the present invention.

本领域的技术人员容易理解,以上所述仅为本发明的较佳实施例而已,并不用以限制本发明,凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等,均应包含在本发明的保护范围之内。It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements, etc., made within the spirit and principles of the present invention, All should be included in the protection scope of the present invention.

Claims (7)

1. A high-speed silicon-germanium photodetector, comprising: the device comprises a doped silicon layer, a germanium absorption region, a doped germanium layer, a contact electrode and a germanium upper electrode;
the doping polarity of the doped silicon layer is opposite to that of the doped germanium layer, and the doped silicon layer, the germanium absorption region and the doped germanium layer are sequentially connected into a vertical PIN junction;
the contact electrode is arranged on the doped silicon layer, the contact electrode surrounds three sides of the germanium absorption region, and the germanium upper electrode is arranged on the doped germanium layer; the contact electrode and the germanium upper electrode collect photo-generated carriers generated by light absorption of the germanium absorption region to form photocurrent;
the distance between each side of the contact electrode and the corresponding side in the germanium absorption region is inversely proportional to the side length of the germanium absorption region.
2. The high speed silicon germanium photodetector of claim 1, wherein the other side of said germanium absorbing region not surrounded by said contact electrode is a channel for light to enter said germanium absorbing region.
3. The high speed silicon germanium photodetector of claim 2 wherein said contact electrode is a U-shaped metal contact electrode.
4. The high speed silicon germanium photodetector of claim 2 wherein said contact electrode is an unsealed square-frame electrode.
5. The high-speed silicon germanium photodetector of claim 1, wherein said doped silicon layer is heavily doped P-type, on the order of 10 20 cm -3
6. The high-speed silicon germanium photodetector of claim 1, wherein said doped germanium layer is heavily doped N-type, on the order of 10 20 cm -3
7. The high speed silicon germanium photodetector of claim 1, wherein said doped silicon layer acts as an optical waveguide to direct incident light into said germanium absorbing region.
CN202311116318.1A 2023-08-31 2023-08-31 A high-speed germanium-silicon photodetector Pending CN116936670A (en)

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