【作者】 李邓玥；

【导师】 赵连城； 李洪涛；

【作者基本信息】 哈尔滨工业大学 ， 信息功能材料与器件， 2013， 博士

【摘要】 InSb基化合物半导体材料具有较高的室温电子迁移率，在电场作用下具有优异的电子输运性能。InSb还具有较小的禁带宽度，是制作3~5μm红外探测器和成像系统的重要材料。另外，InSb及其合金的光发射与一些主要气体如CO、CO2等的基本吸收线相匹配，因而也可使用InSb基发光器件和探测器件制成气体传感系统。近年来，通过在硅基上生长高性能的InSb结构，充分利用硅基材料与InSb材料的优点，实现了功能器件和电路的融合，颇具工程价值而成为纳米尺度器件发展的重要方向。本文利用磁控溅射技术在Si衬底上生长了InSb薄膜和InSb/SiO2/Si XOI结构，综合分析了InSb薄膜和InSb/SiO2/Si异质结的晶体结构，并结合光学和电学性能表征，对材料的结构与性能之间的关系进行了深入研究。论文的主要研究内容包括：首先使用真空电弧炉制备磁控溅射用的InSb靶材，采用调节靶材成分的方法来实现溅射InSb薄膜的正常化学计量比。研究了不同溅射工艺对InSb薄膜结构和性能的影响。随着溅射功率的增大，InSb薄膜由非晶态向晶态转变，晶粒尺寸增大，结晶性变好；当溅射压强逐渐增大时，晶粒尺寸逐渐变小，结晶性变差。在溅射压强为0.6Pa的InSb薄膜中出现了富In的现象。采用快速热退火和常规热退火两种方式对沉积态InSb薄膜进行了退火，并研究了不同退火工艺对薄膜结构和性能的影响。采用快速热退火工艺时，随着退火温度的增加薄膜结晶性变好，晶粒尺寸随之增大，（111）面的择优取向性随之增强。InSb薄膜的透过率随温度的升高而降低，当退火温度从300℃上升到500℃时，InSb的光学带隙从0.22eV红移至0.19eV。不同温度退火的薄膜霍尔测量结果表明，77K和300K下薄膜均为n型，薄膜的迁移率和载流子浓度随着退火温度的上升均有不同程度的增加。在400℃温度下，随着快速热退火时间的增加薄膜晶粒尺寸增大，光学带隙随退火时间的增加逐渐减小。77K和300K下薄膜迁移率均随退火时间的增加而增加，300K下薄膜的载流子浓度随退火时间的增加先增加后减小。与快速热退火工艺相比，采用常规热退火工艺进行退火时，随着退火温度的增加，在相同温度下常规热退火的晶粒尺寸均大于快速热退火的晶粒尺寸。当退火温度从200℃上升到400℃时，薄膜的光学带隙从0.22eV红移至0.2eV。在500℃常规热退火的晶体质量较差，薄膜的光学带隙增大到0.35eV。对比两种不同的退火方式可知，InSb薄膜经常规热退火后的迁移率除200℃退火的样品外，其余皆低于经快速热退火处理后的样品。在400℃温度下，随着常规热退火时间的增加InSb薄膜晶粒尺寸增大，薄膜的光学带隙从0.24eV红移移至0.2eV附近。薄膜的迁移率随退火时间的延长先增加后减小，载流子浓度随退火时间的延长而逐渐增大。分析了快速热退火和常规热退火对晶化过程的影响并计算了快速热退火和常规热退火的晶化激活能，分别为131.5kJ/mol和66.9kJ/mol。利用磁控溅射生长了InSb/SiO2/Si XOI结构，通过透射电镜分析可知，InSb层的厚度为35nm，退火后的薄膜为多晶结构，晶粒尺寸约为13nm。采用高分辨透射技术在退火后的InSb薄膜中观察到了[111]、[220]、[311]三种晶体取向的晶粒，与XRD谱图中衍射峰分析的结果相一致。通过高分辨透射电镜对InSb/SiO2/Si XOI的界面进行分析后可知SiO2层的厚度为4nm。超薄InSb薄膜退火后受纳米尺度晶粒的量子限域效应的影响，光学带隙与InSb晶体的能带带隙值（0.18eV）相比蓝移了0.084eV，带隙值为0.264eV。从I-V特性测量可知，InSb/SiO2/Si XOI结构在室温下表现出明显的二极管整流特性，室温下的开启电压为0.35V，77K下的开启电压为0.55V。分析300K时InSb/SiO2/Si XOI的电子输运机制可知，当电压小于0.35V时为扩散和热电子发射复合机制；电压在0.35-3V之间时为热电子发射机制和空间电荷局域两种模式共同作用；电压大于3V时为空间电荷局域模型机制。更多还原

【Abstract】 InSb-based compound semiconductor material with high room temperatureelectron mobility has excellent electron transport properties under the action of anelectric field. InSb thin films have been used as photo detectors and imagingsystems in the mid infrared wavelength of3-5um since it has a smaller forbiddenband width. Further, InSb and its alloys light-emitting match the fundamentalabsorption lines of some of the main gas such as CO, CO2, etc. Thus InSb-basedlight emitting device and the detector member is made of a gas sensing system mayalso be used. In recent years, high-performance InSb structure has been grown on asilicon substrate, which combine the advantages of silicon and InSb to achieve theintegration of functional devices and circuits, therefore reduced the cost of thedevice, which became an important direction for the development of nano-scaledevices. In this study, InSb films and InSb/SiO2/Si XOI heterostructure aredeposited by magnetron sputtering, the crystal structure of the InSb thin film andInSb/SiO2/Si heterostructure was analyzed, combined with characterization of theoptical and XOI electrical properties, the relationship between the structure andproperties of material are studied in detail. The main content of this thesisincluding:The InSb target was prepared by vacuum arc, the normal stoichiometric ratio ofInSb film was completed by adjusting the target component. The structure andproperties of InSb film are studied under different sputtering process, with theincrease of the sputtering power, InSb film transited from amorphous to crystalline,the grain size increased, the crystallinity got better; on the contrary, when thesputtering pressure is gradually increased, the grain size became smaller, and thecrystallinity was poor. When the sputtering pressure is0.6Pa, the InSb film isIn-rich.As-deposited InSb films were preceded by rapid thermal annealing andconventional annealing; the influence of annealing process was studied. Thecrystallinity was improved with the rapid thermal annealing temperature increased,the grain size increased, and the preferred orientation of the (111) plane along wasalso enhanced. InSb film’s transmittance decreased with increasing temperature.When the annealing temperature increased from300°C to500°C, the optical bandgap of InSb changed from0.22eV to0.19eV. Hall measurements showed that thefilm annealed at77K and300K were n-type. Mobility and carrier concentration ofthe film had different levels of increasing as the annealing temperature raised. At a temperature of400°C, the grain size of film increased with rapid thermal annealingtime increased, the optical band gap gradually decreases. Film migration rateincreased with increasing annealing time at77K and300K, the carrier concentrationfirstly increased and then decreased lately with increasing annealing time at300K.Compared with the rapid thermal annealing process, the grain size of theconventional annealing film at the same temperature were larger than the grain sizeof the rapid thermal annealing film with the annealing temperature increased. Whenthe annealing temperature increased from200°C to400°C, the optical band gap offilm changed from0.22eV to0.2eV. The crystal quality was poor under500°Cconventional annealing, and the optical band gap increased to0.35eV. Comparisonof the two different annealing method shows that the mobility of the InSb film afterthe conventional annealing film with the exception of200°C annealed samples,were less than the sample treated by rapid thermal annealing. At a temperature of400°C, the InSb film grain size increases with conventional thermal annealing timeincreasing, the optical band gap red-shifted from0.24eV to0.2eV. The mobility ofthe films increased with annealing time decreased, the carrier concentrationincreased gradually with the annealing time. According to Avrami-Mehl-Johnsonformula and theoretical Arrhenian formula, the crystallization activation energy is131.5kJ/mol and66.9kJ/mol under rapid thermal annealing or conventional thermalannealing, respectively.InSb/SiO2/Si XOI heterostructure was grown by magnetron sputtering. TEManalysis shows that the thickness of InSb layer is35nm. The film after annealing isthe polycrystalline structure; the grain size is approximately13nm. Using ahigh-resolution transmission electricity microscope technology, the InSb film afterannealing is mainly along [111],[220],[311] three orientations, which is consistentwith the XRD analysis. HRTEM analysis revealed that the thickness of the SiO2layer is about4nm. InSb films annealed were influenced by the nano-scale quantumconfinement effect, the optical band gap of nano-scale InSb is blue-shifted about0.084eV and up to the0.264eV compared to the InSb crystal (0.18eV). From the I-Vcharacteristic measurement, it is shown that InSb/SiO2/Si XOI structure at ambienttemperature exhibited significantly diode rectifying characteristics. At roomtemperature, the turn-on voltage is0.35V, and then at77K it is0.55V. At300K, theelectron transport mechanism of InSb/SiO2/Si XOI structure is thermal electronemission recombination and diffusion mechanism when the voltage is less than0.35V; hot electron emission mechanism and space-charge local modes combinedeffect were mainly mechanism when the voltage is between0.35V and3V; as thevoltage is greater than3V, the local space-charge model mechanism is the mainly mechanism.更多还原