中红外波段高速硅基电光调制器设计与优化（特邀）

作为中红外波段中最接近O波段和C波段的波段,2 μm波段区域逐渐引起人们的广泛关注。主要对2 μm波段的马赫-增德尔型调制器进行优化设计和仿真,根据2 μm波长下光模场分布的特点,选用具有340 nm厚度顶层硅的SOI衬底,结合实际工艺中240 nm硅刻蚀深度,得到宽度为600 nm以及平板层厚度为100 nm的最优脊波导结构。通过优化掺杂浓度和掺杂区位置获得综合性能最优的调制器器件,在4 V反向偏压下器件光损耗为5.17 dB/cm,调制效率为2.86 V·cm,静态消光比为23.8 dB,3dB EO带宽为27.1 GHz。同时,与220 nm厚度顶层硅器件相比较,器件的综合性能更为优越。研究内容为后续器件实际制作提供了依据,也为后续2 μm波段光收发集成模块所需调制器设计提供了新的方向。     

替代衬底上的碲镉汞长波器件暗电流机理

基于暗电流模型,通过变温I-V分析长波器件(截止波长为9~10μm)的暗电流机理和主导机制.实验对比了不同衬底、不同成结方式、不同掺杂异质结构与暗电流成分的相关性.结果表明,对于B+离子注入的平面结汞空位n~+-on-p结构,替代衬底上的碲镉汞(HgCdTe)器件零偏阻抗(R0)在80 K以上与碲锌镉(CdZnTe)基碲镉汞器件结阻抗性能相当.但替代衬底上的HgCdTe因结区内较高的位错,使得从80 K开始缺陷辅助隧穿电流(I_(tat))超过产生复合电流(I_(g-r)),成为暗电流的主要成分.与平面n~+-on-p器件相比,采用原位掺杂组分异质结结构(DLHJ)的p~+-on-n台面器件,因吸收层为n型,少子迁移率较低,能够有效抑制器件的扩散电流.80 K下截止波长9.6μm,中心距30μm,替代衬底上的p~+-on-n台面器件品质参数(R0A)为38Ω·cm2,零偏阻抗较n-on-p结构的CdZnTe基碲镉汞器件高约15倍.但替代衬底上的p+-on-n台面器件仍受体内缺陷影响,在60 K以下较高的Itat成为暗电流主导成分,其R0A相比CdZnTe基n~+-on-p的HgCdTe差了一个数量级.     

新型InGaAs/InP多量子阱异质结构掺杂超晶格光波导调制器

提出一种新型的InGaAs/InP多量子阱异质结构掺杂超晶格光波导调制器。这种结构的器件结合了多量子阱大的光吸收非线性和掺杂超晶格低激发强度的优点,因此具有低驱动偏压差、高通断比率和高的调制响应速率。低的驱动偏压差、小的器件尺寸以及通过扩散形成的分隔接触电极结构(因此可以和传统的平面加工技术兼容),使这种器件特别适合于作为大规模光电集成的单元光调制器和光开关。     

非对称HALO-LDD掺杂石墨烯纳米条带场效应管的电学特性研究(英文)

随着器件沟道尺寸的不断缩小,短沟道效应(SCE)和漏致势垒降低效应(DIBL)对常规类MOSFET结构的石墨烯纳米条带场效应管(GNRFET)影响变大,从而引起器件性能下降。文中提出了一种新型采用非对称HALO-LDD掺杂结构的GNRFET,其能够有效抑制器件中SCE和DIBL,改善器件性能。并采用一种量子力学模型研究GNRFET的电学特性,该模型基于二维NEGF(非平衡格林函数)方程和Poisson方程自洽全量子数值解。结合器件的工作原理,研究了GNRFET的电学特性和器件结构尺寸效应,通过与采用其他掺杂结构的GNRFET的电学特性对比分析,发现这种掺杂结构的石墨烯纳米条带场效应管具有更低的泄漏电流、更低的亚阈值斜率和DIBL以     

用分子束外延法生长HgCdTe双波段红外光敏二极管

本文报道了全分子束外延法生长的HgCdTe可变偏压双波段红外光敏探测器。这种台式器件,即一个n—p—n三层HgCdTe异质结构,经作现场掺杂砷形成p型,掺杂铟形成n型。器件的结构类似于异质结可变基极晶体管。在77K下获得反面照射光谱纯的双波段的探测证明了双色偏压可转换探测器的可行性。通过施加一个-250m V的偏压,选取5.2μm的截止波长(λ_(co)),量子效率(QE)为60％。施加一个+250m V的偏压,选取λ_(co)=7.9μm,量子效率QE为36％。器件的I-V特性可用简单的背对背二极管模式描述。     

碲镉汞p-on-n长波异质结探测器材料的制备研究

报道了碲镉汞p+-on-n长波双层异质结材料和异质结台面器件的研究结果,重点研究了p+-on-n型双层异质结材料制备技术。通过水平滑舟富碲液相外延生长的方法在碲锌镉衬底上原位生长In掺杂碲镉汞n型吸收层材料,然后再采用富汞垂直液相外延技术制备p型As原位掺杂的碲镉汞cap层材料,从而获得p+-on-n型双层异质结材料,并通过湿法腐蚀、台面刻蚀以及钝化等工艺得到碲镉汞 p+-on-n长波异质结台面型器件。p+-on-n异质结器件结构可以有效克服少子寿命偏低等问题,在长波及甚长波波段具有更低的暗电流和更高的R0A值,这对于解决目前长波碲镉汞红外探测器暗电流大、结阻抗低的问题,提高长波及甚长波波段碲镉汞红外焦平面器件的性能具有重要的意义。     

具有记忆功能背景抑制结构的共享型读出电路

甚长波红外(VLWIR)波段富含大气湿度、CO2含量及云层结构和温度轮廓等大量信息,是大气遥感的重要组成部分。为了满足现阶段甚长波红外探测器对读出电路高注入效率、大动态范围、稳定的探测器偏压、长积分时间等需求,设计了一种具有记忆功能背景抑制结构的共享型读出电路。该电路采用22四个相邻的探测器像元共用一个读出电路单元的共享缓冲直接注入级(SBDI)结构,增大了单元电路的面积,在单元内实现了具有记忆功能背景抑制结构的设计,其总积分电容达到8.8 pF,有效延长了积分时间和红外焦平面的信噪比(SNR),并改善了动态范围和对比度。基于HHNEC CZ6H 0.35 m 1P4M标准CMOS工艺,完成了电路的流片制造。仿真及测试结果表明:在50 K温度下电路功能正常,其动态范围大于90 dB,线性度优于99.9%,积分时间可达74 s,达到了设计要求。该读出电路适用于甚长波红外探测器。     

基于电流镜的同步积分模式双色读出结构设计

文章对N+PPN结构的MW／LW双色红外焦平面信号电流同步积分的工作模式，提出了一种双色读出电路输入级的新结构，即在栅调制注入输入级的基础上加以设计改进，采用电流镜对一个独立波段(LW)的信号电流进行两路精确复制，分别用于此波段的信号电流积分、与混合波段信号电流的相减，解决了探测器输出端混合波段信号电流的分离问题，达到了两个波段信号电流同步独立积分的目的。本文就双色电路的输入级结构和工作原理进行了详细的阐述，电路模拟验证的结果表明该电路适用于信号电流大于10nA的双色器件(MW／LW,MW1／MW2，LW1／LW2双色器件)，有较高的精确度(误差<2％)和良好的性能。     

基于光热载流子调控的二维材料红外与太赫兹探测器研究进展

红外和太赫兹具有非常广阔的应用前景,在光谱学、成像、无线通信和遥感等领域发挥着越来越重要的作用。但是,由于红外、太赫兹波段的光子能量低,相关的探测遇到很大困难,所以实现高灵敏、高速和高稳定性的红外太赫兹探测是一个具有挑战性的工作。二维材料由于其高迁移率、带隙可调和表面悬挂键少等特点为红外太赫兹探测提供了新的机遇。基于光热载流子调控的二维材料红外、太赫兹探测器的发展方兴未艾。文中主要介绍了目前基于光热载流子调控的红外、太赫兹探测器的最新研究进展,将从材料、器件结构、响应波段和响应机理等方面展开。     

线性掺杂缓冲层结构VDMOSFET抗单粒子烧毁的仿真研究

通过引入缓冲层可以提高器件的二次击穿电压,进而提高器件发生单粒子烧毁的阈值电压。本文提出采用线性掺杂缓冲层结构。通过准静态雪崩仿真和重离子入射仿真发现,优化线性缓冲层是必要的,对于固定厚度的缓冲层,具有线性掺杂缓冲层结构的器件发生单粒子烧毁时的内部电场强度明显小于优化后的恒定掺杂缓冲层结构的器件。二次击穿电压与寄生晶体管的开启电流明显比具有优化后的恒定掺杂缓冲层结构的器件高。因此,线性掺杂缓冲层结构的器件在抗单粒子烧毁方面更有优势。     

As注入长波碲镉汞红外探测器工艺研究

p-on-n结构的碲镉汞红外探测器具有长的少子寿命、低暗电流、高R0A值等优点,是高温器件、长波甚长波器件发展的重要器件结构.而国内还鲜有砷注入掺杂p-on-n长波HgCdTe探测器的相关报道,为了满足军事、航天等领域对高性能长波探测器迫切的应用需求,针对As离子注入的长波p-on-n碲镉汞红外探测器退火工艺技术进行研...     

Design and development of multicolor MWIR/LWIR and LWIR/VLWIR detector arrays

Multicolor infrared (IR) focal planes are required for high-performance sensor applications. These sensors will require multicolor focal plane arrays (FPAs) that will cover various wavelengths of interest in mid wavelength infrared/long wavelength infrared (MWIR/LWIR) and long wavelength infrared/very long wavelength infrared (LWIR/VLWIR) bands. There has been significant progress in HgCdTe detector technology for multicolor MWIR/LWIR and LWIR/VLWIR FPAs.^1–3 Two-color IR FPAs eliminate the complexity of multiple single-color IR FPAs and provide a significant reduction of weight and power in simpler, reliable, and affordable systems. The complexity of a multicolor IR detector MWIR/LWIR makes the device optimization by trial and error not only impractical but also merely impossible. Too many different geometrical and physical variables need to be considered at the same time. Additionally, material characteristics are only relatively controllable and depend on the process repeatability. In this context, the ability of performing “simulation experiments” where only one or a few parameters are carefully controlled is paramount for a quantum improvement of a new generation of multicolor detectors for various applications.     

Ⅱ类超晶格甚长波红外探测器的发展

由Ⅲ-Ⅴ族半导体材料InAs/GaSb或InAs/Ga1-xInxSb构成的Ⅱ类超晶格(T2SL)光电探测器近年来在理论结构设计及试验器件实现方面进展显著.带隙工程和能带结构工程使得T2SL比碲镉汞材料具有某些优势,特别是很小的窄带隙方面.这些特有的性质,例如较大的有效电子质量、重空穴带和轻空穴带之间的较大间距可以抑制...     

HgCdTe 甚长波红外光伏器件的光电性能

甚长波指的是波长大于14 m的波段,该波段富含大量的信息,包括大气中的湿度和CO2的含量,以及云层的结构和温度的轮廓,这些对大气遥感探测是必须的。采用在CdZnTe衬底上液相外延生长的As掺杂p型材料上进行B+离子注入形成平面结,制成了在液氮温度下,截止波长达到14 m的单元变面积结构和小的焦平面器件。测试结果显示,甚长波器件有反向的开启现象,可能是甚长波器件表面发生反型造成的。单元变面积器件的测试结果显示,甚长波表面电流与体电流是可以比拟的,即表面漏电较大。而变温测试发现,甚长波器件在温度低于50 K时,隧穿电流占主导。在60 m60 m中心距的小面阵器件中,50 m50 m的光敏元I-V特性最差。     

Long wavelength infrared, molecular beam epitaxy, HgCdTe-on-Si diode performance

In the past several years, we have made significant progress in the growth of CdTe buffer layers on Si wafers using molecular beam epitaxy (MBE) as well as the growth of HgCdTe onto this substrate as an alternative to the growth of HgCdTe on bulk CdZnTe wafers. These developments have focused primarily on mid-wavelength infrared (MWIR) HgCdTe and have led to successful demonstrations of high-performance 1024×1024 focal plane arrays (FPAs) using Rockwell Scientific’s double-layer planar heterostructure (DLPH) architecture. We are currently attempting to extend the HgCdTe-on-Si technology to the long wavelength infrared (LWIR) and very long wavelength infrared (VLWIR) regimes. This is made difficult because the large lattice-parameter mismatch between Si and CdTe/HgCdTe results in a high density of threading dislocations (typically, >5E6 cm⁻²), and these dislocations act as conductive pathways for tunneling currents that reduce the R_oA and increase the dark current of the diodes. To assess the current state of the LWIR art, we fabricated a set of test diodes from LWIR HgCdTe grown on Si. Silicon wafers with either CdTe or CdSeTe buffer layers were used. Test results at both 78 K and 40 K are presented and discussed in terms of threading dislocation density. Diode characteristics are compared with LWIR HgCdTe grown on bulk CdZnTe.     

Comparison of normal and inverted band structure HgTe/CdTe superlattices for very long wavelength infrared detectors

The type III band alignment of HgTe/CdTe superlattices leads to the interesting possibility of achieving very long wavelength infrared (VLWIR) (15 μm and longer) cutoff wavelengths with either normal (HgTe layer thickness less than about 70 ? for CdTe layer thickness of 50 ?) or inverted (HgTe thickness greater than about 70 ?) band structures. The inverted band structure superlattices promise even greater cutoff wavelength control than the normal band structure ones. However, the electronic band gaps of inverted band structure superlattices are substantially less than their optical band gaps, leading to large thermal carrier concentrations even at temperature as low as 40 K. These high carrier concentrations in turn give rise to more rapid Auger recombination than normal band structure superlattices with the same cutoff wavelengths. We conclude that the highest performance is expected from VLWIR HgTe/CdTe superlattice-based detectors with normal band structure absorber layers.     

红外探测II类超晶格技术概述(一)

本文简单归纳总结了红外探测II类超晶格材料的发展历史、基本理论、相比MCT材料的优势和材料的基本结构。通过设计6.1系超晶格材料适当的层厚和不同层间应力匹配的界面可以构筑灵活合理的能带结构,打开设计各种符合器件性能要求的新材料结构的可能性(如各种同质结p-i-n结构,双异质结DH、异质结W、M、N、BIRD、CBIRD、p-π-M-N、pBiBn、nBn、XBp、pMp等结构),还可以在一个焦平面阵列(FPA)像元上集成吸收层堆栈实现集成多色/多带探测。T2SL探测器可以满足实现大面阵、高温工作、高性能、多带/多色探测的第三代红外探测器需求,尤其在长波红外(LWIR)和甚长波红外(VLWIR)及双色/多带探测上可以替代MCT。     

Realization of very long wavelength infrared photovoltaic detector arrays on mercury cadmium telluride epitaxial layers grown on Si substrates

This paper proposes a development of n-on-p structures for realizing very long wavelength infrared (VLWIR) detector arrays on mercury cadmium telluride (HgCdTe) epitaxial layers grown on Si substrates. It is shown from a comparative study of zero-bias resistance-area product (R₀A) of diodes in n-on-p and p-on-n configurations that the n-on-p structure has promising potential to control contribution of dislocations, without actually reducing dislocation density below the current level (mid-10⁶ cm⁻²) of HgCdTe/Si material technology. The resulting gain will be in terms of both higher numerical magnitudes of R₀A and its reduced scatter.     

From Long Infrared to Very Long Infrared Wavelength Focal Plane Arrays Made with HgCdTe n + n ?/ p Ion Implantation Technology

This paper aims at studying the feasibility of very long infrared wavelength (VLWIR) (12–18 μm) focal plane arrays using n-on-p planar ion-implanted technology. To explore and analyze the feasibility of such VLWIR detectors, a set of four Cd _x Hg_1−x Te LPE layers with an 18 μ cutoff at 50 K has been processed at Defir (LETI/LIR–Sofradir joint laboratory), using both our “standard” n-on-p process and our improved low dark current process. Several 320 × 256 arrays, 30-μm pitch, have been hybridized on standard Sofradir readout circuits and tested. Small dimension test arrays characterization is also presented. Measured photonic currents with a 20°C black body suggest an internal quantum efficiency above 50%. Typical I(V) curves and thermal evolution of the saturation current are discussed, showing that standard photodiodes remain diffusion limited at low biases for temperatures down to 30 K. Moreover, the dark current gain brought by the improved process is clearly visible for temperatures higher than 40 K. Noise measurements are also discussed showing that a very large majority of detectors appeared background limited under usual illumination and biases. In our opinion, such results demonstrate the feasibility of high-performance complex focal plane arrays in the VLWIR range at medium term.