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Molecular Precursors for the CVD of Gallium and Indium Oxides

用于 CVD 氧化镓和氧化铟的分子前体

基本信息

批准号：
EP/F035675/1
负责人：
Claire Jane Carmalt
金额：
$ 51.56万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FF035675%2F1
关键词：
Molecular Precursors CVD Gallium Indium

项目摘要

The goal of this study is to develop new highly volatile CVD precursors to deposit gallium oxide and indium oxide films free from contamination (e.g. C, F) and for a detailed investigation of the gas sensing and TCO (thermally conductive oxide) properties of the resulting films. Gallium oxide (Ga2O3) is considered to be one of the most ideal materials for application as thin-film gas sensors at high temperature. It is thermally stable and an electrical insulator at room temperature but semiconducting above 400 oC. At temperatures above 900 oC the electric conductivity changes depend on the concentration of oxygen, hence the oxygen concentration can be detected. Oxygen gas sensors have practical use in monitoring and controlling oxygen concentrations in exhaust gases of automobiles, as well as waste gases and chemical processes. Above 400 oC Ga2O3 thin-film operates as a surface-control-type sensor to reducing gases, e.g. CO and EtOH. Therefore, it is possible to switch the function of the sensor with temperature. Indium oxide films are both transparent to visible light and conductive (TCO). Dopants (e.g. Sn) can be used to increase the conductivity of the films and to make them more suitable for applications such as in solid-state optoelectronic devices. Group 13 hydrido species possess several notable characteristics that result in them being attractive as precursors to solid-state materials. Firstly, the lack of metal-carbon bonds has the potential to reduce the amount of carbon impurities in the final material and processing temperatures can potentially be reduced due to the thermally frail metal-hydride bonds. Secondly, group 13 hydrides are attractive as precursors as they are considerably more volatile than alkyl derivatives. Thus, a range of novel volatile hydrido-gallium and indium alkoxide complexes as well as heteroleptic alkoxides will be developed. The deposition of Ga2O3 and In2O3 thin-films from the novel precursors synthesised in this programme via low pressure chemical vapour deposition (LP)CVD and aerosol assisted (AA)CVD will be investigated and the gas sensor properties of the films will be assessed. By utilising a wide range of precursors and deposition techniques we will be able to produce different microstructures and develop a correlation landscape between microstructure and gas sensing response. Indium gallium oxide (GaxInyO3) is an exceptional material for TCO applications with absolute transparency that exceed all other oxides / coupled with extremely high charge mobility. Thin-films of GaxInyO3 will be grown using combinatorial atmospheric pressure (AP)CVD and mixed nanoparticulate Ga2O3 inside host In2O3 by AACVD/APCVD from the novel precursors. We have the ability to lay down thin films using a new combinatorial APCVD reactor to make films of graded composition. This new reactor enables upto 400 different compositions to be made on a single plate in one CVD experiment. This is important as it will enable us to rapidly screen composition space in the gallium-indium oxide system and make idealised and optimised compositions for gas sensing and TCO applications. The ability to optimise composition and hence performance in a single CVD experiment would demonstrate the power of the combinatorial technique. Further we have a new reactor design for making indium oxide with embedded nanoparticles- such as gallium oxide. In this system the aerosol flow enters the deposition chamber below the APCVD gas flow, this has the benefit of allowing composite films to be made in which nanoparticles either present or generated in the aerosol droplet are embedded in the APCVD host film. This combined approach will enable us to investigate different nanoparticle densities, sizes and forms and how these effect the gas sensing properties.

本研究的目标是开发新的高挥发性CVD前驱体，以沉积氧化镓和氧化铟薄膜而不受污染（例如C， F），并详细研究所得薄膜的气敏和TCO（导热氧化物）性能。氧化镓（Ga2O3）被认为是最理想的高温薄膜气体传感器材料之一。它是热稳定的，在室温下是电绝缘体，但在400℃以上是半导体。在900℃以上的温度下，电导率的变化取决于氧的浓度，因此可以检测到氧的浓度。氧气传感器在监测和控制汽车尾气、废气和化学过程中的氧气浓度方面具有实际用途。400℃以上的Ga2O3薄膜可作为表面控制型传感器，用于还原CO和EtOH等气体。因此，可以用温度来切换传感器的功能。氧化铟薄膜对可见光透明且导电（TCO）。掺杂剂（如锡）可用于增加薄膜的导电性，使其更适合于固态光电器件等应用。13族氢化物具有几个显著的特征，使它们成为固态材料的前体。首先，金属-碳键的缺乏有可能减少最终材料中碳杂质的数量，并且由于热脆弱的金属-氢化物键，加工温度可能会降低。其次，13族氢化物作为前体是有吸引力的，因为它们比烷基衍生物挥发性大得多。因此，一系列新的挥发性氢化物-镓和铟醇氧化物配合物以及杂性醇氧化物将被开发出来。通过低压化学气相沉积（LP）CVD和气溶胶辅助（AA）CVD合成的新型前驱体的Ga2O3和In2O3薄膜的沉积将被研究，薄膜的气体传感器性能将被评估。通过利用广泛的前驱体和沉积技术，我们将能够产生不同的微观结构，并在微观结构和气敏响应之间建立相关景观。氧化铟镓（GaxInyO3）是TCO应用的一种特殊材料，具有绝对的透明度，超过所有其他氧化物/加上极高的电荷迁移率。采用组合常压（AP）气相沉积（CVD）和混合纳米颗粒Ga2O3在基体In2O3内的AACVD/APCVD法制备GaxInyO3薄膜。我们有能力使用一个新的组合APCVD反应器来铺层薄膜，以制备梯度成分的薄膜。这种新的反应器可以在一个CVD实验中在单个板上制备多达400种不同的成分。这很重要，因为它将使我们能够快速筛选氧化镓铟系统中的成分空间，并为气敏和TCO应用制作理想和优化的成分。在单个CVD实验中优化组成和性能的能力将证明组合技术的力量。此外，我们还设计了一种新的反应器，用于制造嵌入纳米颗粒的氧化铟——比如氧化镓。在该系统中，气溶胶流进入APCVD气流下方的沉积室，这有一个好处，即允许复合膜的制作，其中存在或产生在气溶胶液滴中的纳米粒子嵌入在APCVD宿主膜中。这种结合的方法将使我们能够研究不同的纳米颗粒密度、大小和形式，以及它们如何影响气敏性能。