原子层沉积LiPON薄膜的表面钝化研究

LiPON是一种重要的固态电解质,然而LiPON薄膜会与空气中的水和CO2发生反应产生Li2CO3,导致器件的电学性能变差.本工作利用X射线光电子能谱研究了通过原子层沉积(ALD)技术生长Al2O3薄膜来钝化LiPON薄膜,并且对比了多种方案:在ALD生长Al2O3薄膜之前对样品表面不做预处理,利用O3作为生长Al2O...     

氧化铝钝化在晶体硅太阳电池中的应用

首先,回顾了氧化铝钝化技术的发展历程,对制备氧化铝钝化薄膜的手段进行了总结,并且详细描述了氧化铝的材料性质和钝化的机理。其次,指出氧化铝薄膜的优点在于优异的场效应钝化特性和良好的化学钝化性质,因此可以应用于低掺和高掺p型硅表面的钝化。此外,氧化铝薄膜及其叠层还具有良好的热稳定性,符合丝网印刷太阳电池的要求。最后,总结了氧化铝薄膜钝化技术在晶体硅太阳电池中的最新研究动态,指出氧化铝钝化薄膜用于工业生产中存在的问题,并针对这些问题提出了有效的解决方案。     

高效太阳电池硅衬底特性对原子层沉积Al2O3薄膜钝化性能的影响

Atom layer deposition （ALD）-Al2O3 thin films are considered effective passivation layers for p-type silicon surfaces. A lower surface recombination rate was obtained through optimizing the deposition parameters. The effects of some of the basic substrate characteristics including material type, bulk resistivity and surface morphology on the passivation performance of ALD-Al2O3 are evaluated in this paper. Surface recombination velocities of 7.8 cm/s and 6.5 cm/s were obtained for p-type and n-type wafers without emitters, respectively. Substrates with bulk resistivity ranging from 1.5 to 4 Ω · cm were all great for such passivation films, and a higher implied Voc of 660 mV on the 3 Ω · cm substrate was achieved. A minority carrier lifetime （MCL） of nearly 10 μs higher was obtained for cells with a polished back surface compared to those with a textured surface, which indicates the necessity of the polishing process for high-efficiency solar cells. For n-type semi-finished solar cells, a lower effective front surface recombination velocity of 31.8 cm/s was acquired, implying the great potential of （ALD）-Al2O3 thin films for high-efficiency n-type solar cells.     

沉积功率和退火工艺对PE-ALD氧化铝薄膜的影响

Al2O3薄膜常用于有机电子器件的稳定化封装.除了薄膜的水气渗透率特性,薄膜的表面粗糙度、润湿性和折射率等性能也会影响薄膜的最终封装效果.采用自制等离子增强原子层沉积(PE-ALD)系统在低温下成功制备了Al2O3薄膜,研究了沉积功率和退火参数对Al2O3薄膜微观形貌和性能的影响.结果表明,Al2O3薄膜的生长速率和折射率随沉积功率的增加分别呈现先增加后下降和不断增加的趋势,当沉积功率为1 800 W时,薄膜的线性生长速率达到0.27 nm/cycle,远高于传统热原子层沉积技术的沉积速率.退火处理不会改变Al2O3薄膜晶态,但改善了薄膜的表面粗糙度,降低了接触角和有机基团红外强度.得到了最佳的PE-ALD薄膜制备工艺条件,实现了对有机发光二极管器件的有效封装.     

电子束辐照下的石墨烯上的原子层沉积Al2O3介质层

为了研究石墨烯与高k介质的结合,使用原子层沉积氧化铝在石墨衬底上。沉积前使用电子束辐照,观测到了氧化铝明显改善的形貌。归因于电子束辐照过程中的石墨层的无定形变化过程。     

EBCMOS钝化层表面残气吸附特性

基于密度泛函理论,研究了电子轰击互补金属氧化物半导体(EBCMOS)钝化层表面的残气吸附机制,并分析其电学特性。结果表明,以Al₂O₃钝化层为例,真空腔内残余气体H₂在Al₂O₃不同表面的吸附为物理吸附,在(001)面的吸附距离最大,吸附强度最低,电荷转移最少。对比CO,N₂,CO₂,H₂O等残余气体分子在(001)表面的吸附结果发现,(001)面对残气分子的吸附均为物理吸附,(001)面相比于其他表面,对残余气体分子有更好的抑制作用,所生成钝化层能提高EBCMOS器件电子倍增层的电荷收集效率。研究结果对研制寿命长而稳定的EBCMOS器件具有理论指导意义。     

原子层沉积法制备微通道板发射层的性能

随着微通道板的不断发展与完善,通过改善传统工艺提升其性能越来越困难,开发提升微通道板性能的新技术迫在眉睫。纳米薄膜材料的发展及其制备技术的成熟为微通道板的发展提供了契机,利用原子层沉积技术在通道内壁沉积一层氧化铝纳米薄膜,作为二次电子发射功能层,可以增强通道内壁的二次电子发射能力,从而提升微通道板的增益性能。通过优化原子层沉积工艺参数可以在微通道板的通道内壁沉积厚度均匀的氧化铝薄膜。研究结果表明,微通道板增益随沉积氧化铝厚度的变化而变化,在氧化铝厚度为60 cycles时,施加偏压800 V时增益可达56 000,约为正常微通道板增益的12倍。     

PEALD制备的Al2O3薄膜在n-TOPCon太阳电池上的钝化性能

对采用等离子体增强原子层沉积(PEALD)法制备的Al2O3薄膜在n型单晶硅隧穿氧化层钝化接触(TOPCon)太阳电池正表面的钝化性能进行了研究.采用少数载流子寿命、X射线电子能谱(XPS)及J-V特性的测试分析,重点研究了 Al2O3沉积温度、薄膜厚度及薄膜形成后不同退火条件对钝化性能的影响,实现了低表面复合速率、良好钝化效果的产业化制备的Al2O3薄膜工艺.研究结果表明,在沉积温度为150℃、膜厚为5 nm、退火温度为450℃时,测试计算得出薄膜中O和Al的原子数之比为2.08,电池发射极正表面复合速率较低,达到了Al2O3钝化的最优效果,并且分析了 Al2O3薄膜的化学态和形成机理.利用其Al2O3薄膜工艺制备的n型单晶硅TOPCon太阳电池开路电压提升了 8 mV,电池的平均光电转换效率达到了 23.30％.     

衬底表面处理对原子层沉积法生长GaN薄膜的影响

采用等离子增强原子层沉积技术于蓝宝石衬底上生长GaN薄膜,研究氮等离子体预处理衬底对薄膜结晶性能的影响.利用X射线衍射仪、扫描电子显微镜、原子力显微镜、X射线光电子能谱仪等手段对薄膜的晶体结构、表面形貌及薄膜成分进行表征和分析.结果表明,经预处理的蓝宝石衬底上生长的GaN薄膜晶体质量明显提高,沿c轴高度择优取向生长;光学带隙约为3.48 eV;薄膜呈n型导电特性,电阻率为2.551×10-2 Ω·cm,载流子浓度高达1.876×1019 cm-3,迁移率为13.04 cm2·V-1·s-1;薄膜中Ga元素主要与N元素以Ga-N键生成GaN.     

Effects of surface passivation during atomic layer deposition of Al2O3 on In0.53Ga0.47As substrates

In this work we investigate the effect of different III-V surface passivation strategies during atomic layer deposition of Al₂O₃. X-ray photoelectron spectroscopy indicates that bare As-decapped and sulfur passivated In_0.53Ga_0.47As present residual oxides on the surface just before the beginning of the Al₂O₃ deposition while the insertion of a Ge interface passivation layer results in an almost oxide free Ge/III-V interface. The study of the initial growth regimes, by means of in situ spectroscopic ellipsometry, shows that the growth of Al₂O₃ on Ge leads to an enhanced initial growth accompanied by the formation of Ge-O-Al species thus affecting the final electrical properties of the stack. Alternatively, deposition on decapped and S-passivated In_0.53Ga_0.47As results in a more controlled growth process. The sulfur passivation leads to a better electrical response of the capacitor that can be associated to a lower oxide/semiconductor interface trap density.     

Effective passivation of defects in Ge-rich SiGe-on-insulator substrates by Al2O3 deposition and subsequent post-annealing

A method of Al₂O₃ deposition and subsequent post-deposition annealing (Al₂O₃-PDA) was proposed to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates, which were fabricated using Ge condensation by dry oxidation. The effect of Al₂O₃-PDA on defect passivation was clarified by surface analysis and electrical evaluation. It was found that Al₂O₃-PDA could not only suppress the surface reaction during Al-PDA in our previous work [Yang H, Wang D, Nakashima H, Hirayama K, Kojima S, Ikeura S. Defect control by Al-deposition and the subsequent post-annealing for SiGe-on-insulator substrates with different Ge fractions. Thin Solid Films 2010; 518: 2342-5.], but could also effectively passivate p-type defects generated during Ge condensation. The concentration in the range of 10¹⁶-10¹⁸ cm⁻³ for defect-induced acceptors and holes in Ge-rich SGOI drastically decreased after Al₂O₃-PDA. As a result of defect passivation, the electrical characteristics of both back-gate p-channel and n-channel metal-oxide-semiconductor field-effect transistors fabricated on Ge-rich SGOI were greatly improved after Al₂O₃-PDA.     

用于GaAs射频集成电路的不同厚度氧化铝MIM 电容的研究

本文研究了不同厚度的氧化铝对MIM电容直流和射频特性的影响。在1MHz下,对于20nm氧化铝MIM电容,其拥有3850 pF/mm₂的高电容密度和可接受的681 ppm/V₂的VCC-α电压系数。1MHz时突出的74 ppm/V₂VCC-α电压系数,8.2GHz谐振频率以及2GHz时41的Q值可以从100nm氧化铝MIM电容获得。采用GaAs工艺以及原子层淀积制造的高性能ALD氧化铝MIM电容很有可能成为GaAs射频集成电路很有前景的候选器件。     

一种具有高能量分辨率Al2O3钝化结区的PIN探测器

提出了一种Al₂O₃钝化结区的PIN探测器,与传统PIN探测器不同的是,在器件正面的pn结和背面的高低结处沉积了10 nm厚的Al₂O₃薄膜。经TCAD仿真结果表明,该探测器具有更低的漏电流和保护环处的电子电流密度,能对高能粒子射线入射产生良好的响应。设计了两种探测器的制备步骤并制备了器件,通过薄膜少子寿命的表征、器件的暗态I-V测试和²⁴¹Am元素能谱测试对其进行了评估。测试结果表明,与传统的PIN探测器相比,Al₂O₃钝化结区的PIN探测器的少子寿命提升至1 061μs,漏电流降低至5 nA,能量分辨率提升至521 eV,表现出更好的探测性能。     

Comparative study of AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors with Al2O3 and HfO2 gate oxide

AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOSHFETs) with Al₂O₃ gate oxide which was deposited by atomic layer deposition (ALD) were fabricated and their performance was then compared with that of AlGaN/GaN MOSHFETs with HfO₂ gate oxide. The capacitance (C)-voltage (V) curve of the Al₂O₃/GaN MOS diodes showed a lower hysteresis and lower interface state density than the C-V curve of the HfO₂/GaN diodes, indicating better quality of the Al₂O₃/GaN interface. The saturation of drain current in the I_D-V_GS relation of the Al₂O₃ AlGaN/GaN MOSHFETs was not as pronounced as that of the HfO₂ AlGaN/GaN MOSHFETs. The gate leakage current of the Al₂O₃ MOSHFET was five to eight orders of magnitude smaller than that of the HfO₂ MOSHFETs.     

插层Al2O3对氧化铪基忆阻器的性能优化及多值特性研究

近年来,氧化铪基忆阻器因其优异的阻变性能及与CMOS工艺兼容等特点而被广泛研究。然而,氧化铪基忆阻器仍存在以下问题:1) 器件良率、可靠性、均一性不足;2) Set和Reset 过程中电流突变,导致多值特性较差。为实现氧化铪基忆阻器的性能优化及多值特性,文章在HfO₂表面生长一层1~5 nm Al₂O₃,构造Al₂O₃/HfO₂双介质层忆阻器,并对HfO₂和Al₂O₃的厚度进行优化,最终得到性能显著提升的Al₂O₃/HfO₂双介质层多值忆阻器。该器件呈现出保持性良好的10个不同电阻态(1×10⁴ s@85℃)。由于氧离子在Al₂O₃层的迁移率更低,限制了氧空位细丝生长速率及宽度,且Al₂O₃具有热增强作用,使氧空位分布更均匀,促使氧空位细丝生成/断裂过程由突变转为渐变。该工作为进一步实现氧化铪基忆阻器的性能优化及多值特性提供了参考。     

采用ALD Al2O3作为栅介质的薄势垒增强型AlGaN/GaN MIS-HEMT

本文报道了高性能的增强型（E-mode）氮化镓（GaN）基金属-绝缘体-半导体高电子迁移率晶体管（MIS-HEMT）,该器件势垒层为5-nm厚的铝镓氮（Al0.3Ga0.7N）,并采用氮化硅（SiN）钝化来控制二维电子气（2DEG）密度。与SiN钝化不同,采用原子层淀积（ALD）技术生长的氧化铝（Al2O3）不会增强异质结中的2DEG密度。刻蚀栅区的SiN介质可以耗尽沟道电子,之后采用ALD Al2O3作为栅介质,可以实现MIS结构。栅长为1 μm的E-mode MIS-HEMT具有657mA/mm的最大饱和电流（IDS）、187mS/mm的最大跨导（gm）和1V的阈值电压（Vth）。与相应的E-mode HEMT对比,由于Al2O3栅介质的引入,使器件的性能得到了很大的提升。本文对于同时实现高的Vth和IDS提供了很好的方法。     

Atomic-layer-deposited Al2O3 and HfO2 on GaN: A comparative study on interfaces and electrical characteristics

Al₂O₃, HfO₂, and composite HfO₂/Al₂O₃ films were deposited on n-type GaN using atomic layer deposition (ALD). The interfacial layer of GaON and HfON was observed between HfO₂ and GaN, whereas the absence of an interfacial layer at Al₂O₃/GaN was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy. The dielectric constants of Al₂O₃, HfO₂, and composite HfO₂/Al₂O₃ calculated from the C-V measurement are 9, 16.5, and 13.8, respectively. The Al₂O₃ employed as a template in the composite structure has suppressed the interfacial layer formation during the subsequent ALD-HfO₂ and effectively reduced the gate leakage current. While the dielectric constant of the composite HfO₂/Al₂O₃ film is lower than that of HfO₂, the composite structure provides sharp oxide/GaN interface without interfacial layer, leading to better electrical properties.