Novel Time-Resolved Thermal Imaging: AlGaN/GaN Heterostructure Field Effect Transistors

通信、雷达、飞机、汽车系统所需任务的日益复杂性得益于在高速器件中使用新型材料。这样的器件，例如在移动的通信基站或相控阵雷达中使用的射频（RF）晶体管，必须满足某些性能标准。如今，电气特性主要用于解决器件开发过程中的挑战，以满足这些标准。然而，电测量确定平均器件特性，而不是关于空间特性（诸如温度和电场不均匀性）的具体信息。如果直接成像的温度和电场分布在一个器件区域是可能的，具有高的时间分辨率，这将打开一个新的维度的调查半导体器件。这对于器件研究人员和开发人员研究和解决限制器件性能的时间依赖性现象将是非常有益的。然而，目前还不存在适当的技术。在拟议的工作中，我们将开发第一个高空间分辨率的时间分辨热探测器的半导体器件成像以往任何时候都建成我们的知识。电场分布将从温度信息中提取。该技术将以AlGaN/GaN HFET为例进行说明，以详细了解这些器件的工作原理以及当前器件的限制因素。例如，我们将获得与AlGaN/GaN HFET电流崩塌相关的载流子捕获信息，但经验表明，其他有趣且可能重要的发现也可能随之而来。

The increasing complexity of tasks required by communication, radar, aircraft, automotive systems benefits from the use of novel materials in high speed devices. Such devices, for example, radio-frequency (RF) transistors used in mobile communication base stations or phased array radars, have to meet certain performance standards. Electrical characterization is mostly used today to tackle challenges in the device development process to meet these standards. Electrical measurements, however, determine average device properties rather than specific information on spatial characteristics such as temperature and electric field inhomogeneities. If direct imaging of temperature and electric field distribution over a device area was possible with high time resolution this would open a new dimension for the investigation of semiconductor devices. This would be of great benefit to device researchers and developers to study and tackle time-dependent phenomena limiting device performance. Adequate techniques, however, are not existent at present. In the proposed work we will develop the first high-spatial resolution time-resolved thermal prober for semiconductor device imaging ever built to our knowledge. Electric field distribution will be extracted from the temperature information. The technique will be illustrated on the example of the topical AlGaN/GaN HFETs to learn more about how these devices operate in detail and what limiting factors for current devices are. For example, we will obtain information about carrier trapping related to AlGaN/GaN HFET current collapse, but experience shows that other interesting and potentially important discoveries are likely to result as well.