Laser lifted off III-Nitride and GaN circuits to enable next generation chargers, electric vehicle drives, and wearable electronics

激光剥离 III 族氮化物和 GaN 电路，以实现下一代充电器、电动汽车驱动器和可穿戴电子产品

• 批准号: 2246582
• 负责人: MVS Chandrashekhar
• 金额: $ 50万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2246582&HistoricalAwards=false
• 关键词: Laser; lifted; off; III; Nitride

AlxGa1-xN semiconductors have extreme properties such as high heat removal, high temperature operation, and high current/voltage handling that are ideal for high power compact electronics in electric vehicles. These extreme properties make them excellent for low power applications such as wearables beyond traditional silicon as validated by the emergence of GaN chargers in consumer electronics. Further scaling of device performance with Al content is currently limited by the wafers on which AlxGa1-xN active layer coatings are produced. By removing the wafer and transferring ultrathin active coatings to application specific engineered surfaces, can the full promise of AlGaN’s superior properties be realized in ultra-compact devices? This question will be answered using a patent pending laser liftoff (LLO) AlGaN transfer developed by our team to remove the growth wafer. If successful, our work would transform power transistors for electric vehicles and power grid applications and could lead to the first practical wearable III-Nitride devices from this Nobel winning material system that led to the 2014 Physics prize for the blue LED. Part of this work will be performed by Engineering undergraduates in collaboration with the nation’s best department of Exercise Science and could enable tech transfer of what could be the first application of flexible III-N in healthcare.This work will be performed in the following 3 thrusts.1. Characterizing steady state and transient thermal performance of AlGaN channel transistors by transferring/soldering to Cu heat sinks. This will eliminate the series thermal/electrical resistances of the substrate, reducing thermal time constants from the ms range to the us range. These are suitable for kHz-MHz switching applications without significant temperature rise, a crucial requirement in deep-scaled power electronics that can reach the ideal performance codified in the Baliga Figure of merit.2. Piezoelectric sensing on flexible substrates by transferring depletion mode high-electron mobility transistors (HEMTs) to flexible polyethylene terephthalate (PET). By flexing the AlGaN heterojunction, piezoelectric charge in the channel changes, an effect amplified by the transistor Given the ~1A/mm drive we have obtained for LLO transferred AlGaN/GaN transistors, and PET’s known high critical breakdown field 5MV/cm, we enable new functionalities previously not possible in flexible electronics. We will mount this device on human participants to evaluate the viability of wearable III-N heart rate sensors as a piezoelectric stethoscope.3. Integration of visible III-N emitters and photodetectors in a single package using a LLO pick and place approach to demonstrate a flexible III-N photonic circuit. This will be used to develop an understanding of bandwidth limiting defects induced by LLO and packaging in low-leakage circuits. Defect studies will also inform the other case studies to determine the ultimate bandwidth and power handling capabilities of AlGaN devices. A key issue is that of strain relief induced damage from the highly traumatic laser liftoff and transfer process. This is a problem that we have minimized through our preliminary enabling research, although it is a key problem that will limit the viability of this technology.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

AlxGa1-xN半导体具有高散热、高温操作和高电流/电压处理等极端特性，是电动汽车中大功率紧凑型电子产品的理想选择。这些极端的特性使它们非常适合于低功耗应用，如传统硅以外的可穿戴设备，消费电子产品中出现的GaN充电器证实了这一点。随着Al含量的增加，器件性能的进一步扩展目前受到其上产生AlxGa1-xN有源层涂层的晶片的限制。通过去除晶片并将超薄的活性涂层转移到特定于应用的工程表面，AlGaN优异性能的全部承诺能否在超紧凑设备中实现？这个问题的答案将使用我们团队开发的正在申请专利的激光发射(LLO)AlGaN转移来去除生长晶片。如果成功，我们的工作将改变电动汽车和电网应用的功率晶体管，并可能带来第一个实用的可穿戴III-氮化物设备，这种获得诺贝尔奖的材料系统导致了2014年蓝色LED物理学奖。这项工作的一部分将由工程本科生与全国最好的运动科学系合作完成，并可能使灵活的III-N在医疗保健中的首次应用成为可能。这项工作将在以下三个方面进行。通过向铜散热器转移/焊接来表征AlGaN沟道晶体管的稳态和暂态热性能。这将消除衬底的串联热阻/电阻，将热时间常数从ms范围降低到us范围。这些器件适用于khz-MHz开关应用，而不会出现显著的温升，这是能够达到理想性能的深度电力电子产品的关键要求。通过将耗尽型高电子迁移率晶体管(HEMTs)转移到柔性聚对苯二甲酸乙二醇酯(PET)上，在柔性基板上进行压电传感。通过弯曲AlGaN异质结，沟道中的压电电荷改变，这种效应被晶体管放大，我们已经为LLO转移的AlGaN/GaN晶体管获得了~1A/mm的驱动，以及PET已知的高临界击穿电场5 mV/cm，我们实现了以前在柔性电子学中不可能实现的新功能。我们将把这个装置安装在人类参与者身上，以评估可穿戴的III-N心率传感器作为压电式听诊器的可行性。使用LLO拾取和放置方法将可见的III-N发射器和光电探测器集成在单个封装中，以演示灵活的III-N光子电路。这将被用来发展对低泄漏电路中的LLO和封装引起的带宽限制缺陷的理解。缺陷研究还将为其他案例研究提供参考，以确定AlGaN设备的最终带宽和功率处理能力。一个关键的问题是高度创伤的激光发射和转移过程中的应变缓解引起的损伤。这是一个我们通过初步的使能研究将这个问题最小化的问题，尽管这是一个将限制这项技术的可行性的关键问题。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。