【作者】 袁志钟；

【导师】 杨德仁； 阙端麟；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2007， 博士

【摘要】 随着集成电路按照摩尔定律继续朝着尺寸更小、处理速度更快、成本更低的方向发展,芯片中的器件集成度越来越高,相应的金属互连结构的复杂程度和长度都达到了惊人的水平,随之带来的层间干扰、能量耗散、信号延迟等问题越来越严重;而且特征尺寸的缩小,将导致平面CMOS的寄生电阻和电容将超过其本身的沟道电阻和电容。另外,全球光通讯的飞速发展,使得短距离信号传输所使用的金属互连成为信号传输“瓶颈”。再有,集成电路的发展不仅体现在器件集成度的提高,而且反映在应用范围的扩大,例如在探测、力学、流体等方面的拓展应用,特别是在光学方面的应用。所有这些问题和挑战都需要硅基的光电集成系统来解决,而硅基发光器件成为了这类系统的关键,也是本论文的研究内容。本文利用离子注入工艺制备了硅基发光材料和器件,包括硅pn结、稀土离子Tb³⁺注入SiN_x和SnO₂薄膜,并研究其发光性能,得到了以下创新性结果:首先,通过离子注入和退火的方法制备了不同的硅pn结,对其进行低温、室温光致发光的研究,利用透射电镜观察了硅pn结中的缺陷,并且对硅pn结进行了室温电子束诱生电流的测试。研究发现:硅pn结的发光和注入离子的类型没有关系,其发光强度随着离子注入剂量的增大而先增强后减弱。对于退火处理,常规炉退火比快速热退火更能得到比较强的发光,而氢退火可以进一步提高发光强度,并且退火温度应该控制在950～1100℃范围内。低温下,硅pn结束缚激子的发光峰得到了增强。经过高温退火后,在硅pn结的离子注入区域有位错环存在,该区域在室温下有载流子复合,而没有位错本身的发光峰,证明了位错环边缘的量子限域效应是硅pn结室温发光的主要机制。其次,通过PECVD（等离子体增强化学气相沉积）的方法制备SiN_x薄膜,并用离子注入在薄膜中引入Tb³⁺离子,研究了退火温度和测试温度对该SiN_x:Tb³⁺体系发光性能的影响。通过控制PECVD工艺中反应气体的比例,沉积了不同Si含量的SiN_x薄膜,并研究了这些不同的SiN_x薄膜对Tb₃₊发光的影响。结果表明:在室温下SiN_x:Tb³⁺体系能够得到Tb³⁺离子的⁵D₄→⁷F_k（k=6-3）系列的发光峰,其发光强度随着退火温度的上升而增强（≤1000℃）,该体系的发光几乎没有温度淬灭效应。进一步地,薄膜中含有较少的氧、缺陷态能量传递、载流子辅助以及较短的发光寿命等因素是SiN_x:Tb³⁺体系中Tb³⁺发光增强的原因。对于富硅的SiN_x薄膜,由于该类薄膜在高温退火时容易被氧化,并且有纳米Si颗粒从SiN_x基体中析出,导致了Tb³⁺发光强度的降低。最后,利用高温氧化和RMS（反应磁控溅射）的方法制备了不同的SnO₂薄膜,表征了这些薄膜的微观形貌并分析了薄膜的形成机理,研究了SnO₂薄膜室温的光致和电致发光性能;另外利用离子注入和退火制备了SnO₂:Tb³⁺薄膜,并表征了室温下它们的发光性能。结果表明:金属Sn薄膜在经过1000℃的高温氧化后得到纯的四方金红石结构SnO₂薄膜,存在位于590 nm的氧空位等缺陷相关的发光峰,而且在氧气中长时间退火会导致该发光峰的减弱。RMS制备的SnO₂薄膜在经过高温退火后也可以观察到590 nm的缺陷发光。正向偏置情况下,SnO₂╱p-Si异质结在可获得电致发光。对于SnO₂:Tb³⁺薄膜,经过1000℃的高温退火后,发现了SnO₂的氧空位缺陷发光和Tb³⁺发光共存的现象。另外,通过磷扩散工艺,可以提高SnO₂:Tb³⁺薄膜中Tb³⁺的发光,并抑制SnO₂的缺陷发光。更多还原

【Abstract】 Nowadays,more and more transistors are integrated in chips as the integrated circuit advances according to the Moore’s law.Chips become smaller,faster and cheaper.At the same time,the structure and length of the metal interconnection become overwhelming,which will worse problems such as cross talk,energy dissipation,etc.Moreover,the parasitic resistence and capacitance of the planar CMOS will exceed its channel resistence and capacitance with the scaling of feature size.On the other hand,the ever-growing global optical communication is severely hampered by the "bottleneck" of the data transmission of short-distance metal interconnection.Finally,the development of the integrated circuit includes not only the increased integration level of ultra-large-scale integrated circuits （ULSIs）but also the expanding of applications such as sensors,mechanics,fluid, and optics,etc.The chips need to have the function to process optical singles in optics system.All these challenges require the emergence of silicon optoelectronics system,among which the silicon-based light emitting device is the key opponent and therefore,the main objective of this thesis.Silicon-based light emitting materials and devices,including silicon pn junction,rare-earth Tb³⁺doped SiN_x and SnO₂ films,were fabricated by ion-implantation and their light emission properties were studied in this thesis and some significant results were achieved as follows:Firstly,silicon pn junctions were prepared by ion-implantation and subsequent annealing process and their low temperature and room-temperature photoluminescence（PL）properties wereinvestigated.The defect microstructures and carrier recombination at dislocation loops region were characterized by transmission electron microscope（TEM）and electron beam induced current （EBIC）,respectively.Results show that the light emission of pn junction is independent of ion types（B or P）.PL intensity firstly increases and then drops down with the increasing ion-implantation dose.PL intensity of pn junction prepared by furnace annealing is higher than that by rapid thermal annealing （RTA）.And hydrogen annealing can further improve the light emission intensity. The annealing temperature should be controlled in the range of 950-1100℃.The light mission from bounded excitons at low temperature is enhanced.After ion-implantation and high temperature annealing,dislocation loops are formed in the pn junction.Carrier recombination at the dislocation loop region is intense at room-temperature.No dislocation-related luminescence is found.The quantum confinement effect at the edge of dislocation loops is the main mechanism of the light emission from silicon pn diode at room-temperature.Secondly,SiN_x films were deposited by plasma-enhanced chemical vapor deposition（PECVD）and Tb³⁺ions were introduced by ion-implantation.The effects of post annealing on luminescence properties of the SiN_x:Tb³⁺thin films were investigated.Furthermore,SiN_x films with different silicon concentrations were deposited by PECVD with varying reactive gas ratio of SiH₄ to NH₃.And the effects of these different SiN_x substrates on the light emission of Tb³⁺ions were measured.Results show that ⁵D₄→⁷F_k（k=6-3）series luminescence lines of Tb³⁺ions is observed in SiN_x:Tb³⁺films and the PL intensity increases with annealing temperature（≤1000℃）.The SiN_x:Tb³⁺thin films have little temperature quenching of light emission.Little oxygen content,energy transfer from defect related states,carrier mediated and short light emission lifetime are the reasons for the improved light emission of Tb³⁺in SiN_x:Tb³⁺film.Light emission of Tb³⁺ions can be found in different SiN_x host materials.But in silicon rich SiN_x（SRSN）films,silicon nanocrystals precipitate from the matrix after annealing at high temperature.And the SRSN film is easy to be oxidized.The PL intensity of the Tb³⁺is decreased by the two factors. Thirdly,SnO₂ thin films were fabricated by high temperature oxidation and reactive magnetron sputtering（RMS）.Microstructures and formation mechanisms of these films were characterized and analyzed,respectively.Room-temperature PL and electroluminescence（EL）of SnO₂ films were studied.Moreover,Tb³⁺ doped SnO₂ films(SnO₂:Tb³⁺)were prepared by ion-implantation and subsequent annealing process.And its room-temperature light emission properties were investigated.Results show that pure tetragonal rutile structure SnO₂ films are formed by oxidation of Sn films at 1000℃and intense oxygen vacancy related luminescence at 590 nm are detected at room-temperature.The luminescence intensity of this line decreases with the increasing of oxidation time.The light emission at about 590 nm is also observed in SnO₂ films prepared by RMS and high-temperature annealing.The SnO₂ film is proved to be a good candidate of silicon-based luminescent materials by the EL of SnO₂/p-Si heterojunction when forward-biased.The light emission from Tb³⁺ions from SnO₂:Tb³⁺film annealed at 1000℃is observed and coexists with the host SnO₂ defect luminescence.The light emission of Tb³⁺ions is enhanced and the light emission of the defect-related luminescence from SnO₂ is suppressed by the P diffusion into the SnO₂:Tb³⁺ films.更多还原