Van der Waals Ga2O3 functional materials epitaxy: Revolutionary power electronics

范德华 Ga2O3 功能材料外延：革命性的电力电子学

• 批准号: EP/X015882/1
• 负责人: Martin Kuball
• 金额: $ 25.67万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX015882%2F1
• 关键词: Van; der; Waals; Ga2O3; functional

The imminent climate risks for our planet have been highlighted by the UN's Intergovernmental Panel on Climate Change (IPCC) calling it "code red for humanity" in its scientific report in August 2021. Presently, nearly all energy conversion power electronics use Silicon (Si), which is relatively inefficient, wasting energy as heat. In fact, 72% of global primary energy consumption is wasted, of which 20% could be saved with new power electronics! Wide bandgap devices using GaN and SiC are entering the market, but they either do not sustain high enough voltages or are too expensive for widespread use, e.g., in smart grids. Ultrawide bandgap Gallium Oxide (Ga2O3), with efficiency far exceeding that of narrow bandgap Si, has emerged as a transformative contender with low cost and >1-2 kV, even 10 kV voltage capability, with potential for a massive >100x reduction in power conversion efficiency losses. Considering Ga2O3's high Baliga figure of merit, the metric determining how beneficial a material is for power devices, it has potential to even exceed current wide bandgap power devices (GaN, SiC), now replacing incumbent Si power electronics, by more than a factor of 5-10 in performance.In this project, we target high voltage power devices using van der Waals epitaxy of functional Ga2O3 as a transformative and revolutionary vehicle to open a new research field for low cost high voltage power devices. This form of epitaxy uses an intermediate layer, which reduces the substrate-epitaxial layer interaction, enabling growth of the epitaxial layer onto a foreign material with different crystal structure at the wafer-level, potentially followed by layer transfer to other beneficial substrates, which would otherwise not be possible. If successful this will enable for the first time even >10kV low cost power electronics devices, e.g. for smart grids, i.e., a high reward but the approach taken is highly speculative: (i) Do van der Waals materials survive the reactive ambient of a Ga2O3 MOCVD chamber? (ii) does potential damage to the van der Waals material impact the subsequent device quality? (iii) can we control Ga2O3's polytypes during growth? (iv) do van der Waals grown interfaces provide high enough electron and phonon transport through them, and can these be optimized or mitigated for e.g. using growth conditions or h-BN thickness, or during a layer transfer? If successful, subsequent layer transfer would allow heterogeneous integration of Ga2O3 with numerous low-cost high thermal conductivity substrates such as poly-AlN and poly-diamond to revolutionize device heat sinking. Use of p-type substrates would open the design space to bipolar devices, even superjunctions, i.e. device concepts which have transformed Si power electronics, concepts which have rarely being able to venture beyond Si, a major impact if we are successful. Lateral devices will be used to validate the effectiveness of the integration, with routes to possible commercialization of high performance devices to be explored through our industrial partnership with Dynex Semiconductor. Vertical devices (with improved power density over lateral configurations, attractive for power electronics applications) will also be demonstrated.The programme also marks a key milestone from a sustainability perspective, within a circular economy; van der Waals epitaxy or epilayer transfer used for the active devices will minimize the need for Ga2O3 substrates, to transfer to substrates with less sustainability issues (elemental Ga may become scarce within 100 years), minimizing the amount of Ga being used in power devices. Successful demonstration of heterogeneous integration of Ga2O3 by van der Waals epitaxy will also pave the way for low-cost, wafer-level integration with other ultrawide bandgap materials (e.g. single crystalline AlGaN, AlN, diamond), offering the potential to strongly reduce the contribution of inefficiency in power electronics to global energy consumption.

联合国政府间气候变化专门委员会 (IPCC) 在 2021 年 8 月的科学报告中强调了地球面临的迫在眉睫的气候风险，称之为“人类红色代码”。目前，几乎所有能源转换电力电子设备都使用硅 (Si) ，效率相对较低，以热量的形式浪费能源。事实上，全球一次能源消耗的 72% 被浪费了，其中 20% 可以通过新的电力电子设备节省！使用 GaN 和 SiC 的宽带隙器件正在进入市场，但它们要么无法维持足够高的电压，要么过于昂贵，无法广泛使用，例如在智能电网中。超宽带隙氧化镓 (Ga2O3) 的效率远远超过窄带隙硅，已成为低成本、>1-2 kV、甚至 10 kV 电压能力的变革性竞争者，并且有可能大幅降低 >100 倍的功耗转换效率损失。考虑到 Ga2O3 的高 Baliga 品质因数（决定材料对功率器件的益处程度的指标），它甚至有可能超过当前的宽带隙功率器件（GaN、SiC），从而取代现有的 Si 功率电子器件，超过一个因子性能5-10。在这个项目中，我们的目标是使用功能性Ga2O3范德华外延的高压功率器件作为变革性和革命性的载体，为低成本高压功率开辟新的研究领域设备。这种形式的外延使用中间层，减少了衬底与外延层的相互作用，使得外延层能够在晶圆级上生长到具有不同晶体结构的异质材料上，随后可能会层转移到其他有益的衬底上，这将否则不可能。如果成功，这将首次实现 >10kV 的低成本电力电子设备，例如对于智能电网，即高回报，但所采取的方法具有高度推测性：(i) 范德华材料能否在 Ga2O3 MOCVD 室的反应环境中存活？ (ii) 范德华材料的潜在损坏是否会影响后续器件的质量？ (iii) 我们可以在生长过程中控制Ga2O3 的多型吗？ (iv) 范德华生长的界面是否提供足够高的电子和声子传输通过它们，并且这些可以被优化或减轻，例如使用生长条件或 h-BN 厚度，或在层转移期间？如果成功，后续的层转移将允许 Ga2O3 与众多低成本高导热基板（例如聚 AlN 和聚金刚石）异质集成，从而彻底改变器件散热。 p型衬底的使用将为双极器件甚至超级结打开设计空间，即改变硅电力电子器件的器件概念，这些概念很少能够超越硅，如果我们成功的话，这将产生重大影响。横向器件将用于验证集成的有效性，并通过我们与 Dynex Semiconductor 的工业合作伙伴关系探索高性能器件可能商业化的途径。还将展示垂直设备（与横向配置相比具有更高的功率密度，对电力电子应用有吸引力）。从可持续发展的角度来看，该计划还标志着循环经济中的一个重要里程碑；用于有源器件的范德华外延或外延层转移将最大限度地减少对 Ga2O3 衬底的需求，转移到可持续性问题较少的衬底（元素 Ga 可能在 100 年内变得稀缺），从而最大限度地减少功率器件中使用的 Ga 量。范德华外延异质集成Ga2O3的成功演示也将为与其他超宽带隙材料（例如单晶AlGaN、AlN、金刚石）的低成本、晶圆级集成铺平道路，提供了大幅降低贡献的潜力电力电子设备效率低下对全球能源消耗的影响。

项目成果

Epitaxial Growth of (-201) ß-Ga 2 O 3 on (001) Diamond Substrates

(-201) -Ga 2 O 3 在 (001) 金刚石基底上的外延生长

• DOI: http://dx.10.1021/acs.cgd.3c00972
• 发表时间: 2023
• 期刊: Crystal Growth & Design
• 影响因子: 3.8
• 作者: Nandi A