锗/硅雪崩光电探测器的研究

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	锗/硅雪崩光电探测器的研究
	武文周
学位类型	博士
导师	成步文
	2017-05-31
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位专业	微电子学与固体电子学
关键词	硅基光电子锗硅近红外雪崩光电探测器
其他摘要	随着半导体技术的发展和芯片集成度的提高，和因此而迅猛发展起的大数据等信息处理技术，大容量传输技术越发显得重要。低功耗、大带宽、低噪声并且抗电磁干扰的光电子技术越发得到产业界的重视。在芯片传输延迟，降低功耗和增大带宽方面，光互连技术相比于传统的电互连技术具有得天独厚的优势，并被视为突破传统电互联瓶颈的解决方案，并已经有成熟的方案应用于高性能计算机和数据中心。此外，随着21世纪信息产业的蓬勃发展，互联网、云计算、物联网等新技术都对通信技术提出了极高的要求，包括更高的通信带宽，更大的网络稳定性，以及更高的用户覆盖率，和更加廉价的成本等等，这为光互连技术提供了广阔的应用平台。目前光电子技术中广泛应用的是InP基器件和芯片。但由于其成本高昂，不利于大面积普及应用。相比而言，成本低廉，且具有较高可靠性的Si基光电子技术受到研究人员的重视。因此以CMOS工艺为基础的Si基光电子技术在近10年内得到迅速的发展，并得到了包括Intel、IBM、Luxtera、Kotura、Compass-EOS、华为等公司的重视和科研投入。光电探测器作为无源光网络（PON）中的光电信号转化的重要环节，其技术指标的要求也随着产业的发展而迅速提高。光纤入x（楼、户……）（fiber to the x , FTTx: building, house…）方案的普及度提高，对于具有内部光增益的雪崩光电探测器提出极高的要求。同时在光网络的普及中，4×10Gbits/s方案已经非常普及，下一代的4×25Gbits/s的PIN-PD方案也在铺展中。与此相对的，2016年SiFotonics科技公司首先提出了25Gbits/s的Ge/Si APD-PD封装集成方案。高性能的Ge/Si APD需要深入的研究。同时，作为近红外光探测器，Ge/Si雪崩光电探测器在放大光信号以及器件成本上有一定的优势。在近红外光弱光探测方面， Ge/Si雪崩光电探测器也有很好的应用前景。本论文围绕锗/硅雪崩光电探测器开展研究，理论模拟和设计了具有高的增益带宽积的隧穿型锗硅雪崩光电探测器，和具有特殊电场限制效应、高雪崩增益的横向锗/硅雪崩光电探测器，并实验制备了吸收区、电荷区、倍增区分离结构的锗/硅雪崩光电探测器。主要创新点如下： (1) 针对SACM APD结构在雪崩增益较大时，增益和带宽之间相互制约的关系，在经典的SACM结构中引入了势垒阻挡层，利用高频隧穿特性实现了-3dB带宽的提升，进而提高了器件的增益带宽积。势垒层厚度2nm，阻挡层禁带宽度为4.5eV的隧穿Ge/Si APD的最大增益带宽积最大为286GHz，相同仿真条件下无势垒层APD为242GHz，实现了18%的明显的增加。 (2) 针对SACM APD结构受空间电荷效应的影响雪崩增益过小，探测微弱光信号时受限的问题，提出了一种新型的横向Ge/Si APD结构。通过理论研究和仿真探索，发现此结构中通过独特的Ge/Si界面限制效应实现电场分离，从而实现可控的雪崩倍增。器件在Si衬底掺杂浓度为2 × 10¹⁶cm⁻³且Si台面厚度为0.3μm时可以在-22.2dBm的1.55μm入射光下实现246倍增益，是相同倍增区长度和入射面积的SACM Ge/Si APD的3.57倍，雪崩击穿电压下的暗电流为5.93μA，也比同样条件下SACM Ge/Si APD的雪崩击穿电压下的暗电流12.7μA要小。通过对材料质量以及掺杂的合理控制，以及优化半导体器件制备工艺，制备了SACM APD，并测量了室温与150K-270K的低温I-V特性。直径30μm器件-1V下暗电流为0.492nA，暗电流密度为69.6μA/cm²。直径50μm器件-1V下暗电流为1.42nA，暗电流密度为72.3μA/cm²。-10dBm和-24.8 dBm入射光强下，直径50μm APD在0.9BV下的光增益分别为4.1和4.7。器件在不同功率光入射下均表现出明显的倍增效果。器件的击穿电压变温系数为10mV/K。具有较低的暗电流密度和很好的热稳定性。; With the development of semiconductor technology, chip integration and information processing technology including the big data, transmission technology of voluminous data becomes more and more important. Photonics technology with low power cost, high bandwidth, low noise and anti-electromagnetic interference is receiving attention from the industrial circle. The optical interconnection technology is considered to be one of the best solutions to break through the bottleneck of electrical interconnection, with advantage over classic electrical interconnection on low signal delay, power cost and high bandwidth, and is taken used in high-performance computing and data center. what's more, the development in information industry in the 21st century especially in new technology like internet, cloud computing and internet of things makes extreme requests on communication technology, including higher communication bandwidth, higher stability, higher user cover rate and lower cost in money, which pave the way to higher level application platform for optical interconnection. The most popular Photonics technology in use is the InP base devices and chips. But because of the high price in material and process technology, the InP base device is not suitable for large scaled application. Compared with the InP base device, the Si base device with lower cost and higher stability is given attention from researchers. As a result, Si photonics based on CMOS process is quickly developed in recent 10 years, and is payed attention to by big international companies including Intel, IBM, Luxtera, Kotura, Compass-EOS and Huawei. As one of the key assembly unit in the passive optical network, detectors need improvements on bandwidth and sensitivity, and the requirement is rising with the development of the industry. With inner high gain of signal, the avalanche photodiodes can improve the coverage rate and reduce the bit error rate in the optical communication networks. The development of FTTx (fiber to the x: home, building, ...), the requirement on the avalanche photodiodes is improving. In the recent development of optical network, the 4×10Gbits/s scheme is popularized and the next of 4×25Gbits/s scheme of PIN-PD is paving its way for practical application. And the 25Gbits/s Ge/Si APD device packing is exhibited by the SiFotonics Inc. in 2016. High speed Ge/Si APD still needs improvement in performance. What's more, Ge/Si APD is promising in low light level near infrared detection. This thesis focused on the research of Ge/Si APD, studied the tunneling APD with high frequency response and big gain-bandwidth product, the lateral APD with special mechanism of high field confinement and high gain by using theoretical simulation. And we prepared the Ge/Si separate absorption charge and multiplication APD. The main results and conclusions are described as follows: (1) To solve the Gain-bandwidth product restriction of SACM APD when the avalanche gain is high, we come up with a Ge/Si APD with an ultra-thin barrier layer, and improve the high frequency response and gain-bandwidth product by bringing in the high frequency tunneling effect. When the barrier layer thickness was 2nm and bandgap of the barrier layer is 4.5eV, the tunneling APD reached the maximum value of the GBP of 286GHz. Compared with the structure without barrier layer with GBP value of 242GHz, the optimized tunneling APD improved the GBP with 18%. (2) To improve the avalanche gain of SACM APD restricted by space charge effect, we design a lateral APD structure. Through theoretical research and simulation analysis, we find special electric separation mechanism of the structure. And the optimized lateral APD structure with 0.3μm-thick Si mesa and substrate Si impurity concentration of 2×1016cm-3 can reach high gain of 246 under -22.2dBm 1.55μm incident light,3.5 times of the SACM APD with same size of multiplication and absorption region, with high electric field confinement from the Ge/Si hetero-structure interface. (3) By controlling the material property, impurity distribution and optimizing the semiconductor device fabrication process, we designed and prepared the test device of the Ge/Si SACM APD structure. The properties of I-V curve at room temperature and variable temperature from 150K to 270K is tested. The dark current at -1V of the SACM APD with a diameter of 30μm and 50μm is 0.492nA and 1.42nA, the current density is 69.6μA/cm2 and 72.3μm/cm2 respectively. The device has good avalanche effect under different incident light power. The changing rate of breakdown voltage with temperature is 10mV/K, showing good heat stability of the device.
学科领域	半导体器件
语种	中文
公开日期	2017-06-05
文献类型	学位论文
条目标识符	http://ir.semi.ac.cn/handle/172111/28246
专题	光电子研究发展中心
推荐引用方式 GB/T 7714	武文周. 锗/硅雪崩光电探测器的研究[D]. 北京. 中国科学院研究生院,2017.

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