Combining two- and three-dimensional (2D/3D) materials provides a unique route to enabling next-generation hot electron transistors (HETs)—a vertical ballistic device, promising for high-frequency applications since they are not limited by electron velocity saturation, fabrication limitations, or short channel effects. The early demonstrations of HETs suffered from poor material and interface qualities and thick device components. The revival of the HET, with a cut-off predicted frequency above 1 THz, can be correlated with the arrival of 2D materials. Here, we discuss HET operating principles, examine HET material architectures with and without tunneling barriers, and review heterostructure considerations. We discuss material and interface properties that control barrier and base performance and critically review recent 2D/3D HETs for tunneling efficiency, output current density, current gain, and output conductance. Finally, we provide an overview of 2D and 3D semiconductors that form Schottky barriers with graphene that may be utilized as a collector while considering the device physics and growth issues.

中文翻译：

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2D/3D 热电子晶体管设计的材料考虑

结合二维和三维 (2D/3D) 材料提供了一条独特的途径来实现下一代热电子晶体管 (HET)——一种垂直弹道器件，有望用于高频应用，因为它们不受电子速度饱和的限制，制造限制或短沟道效应。HET 的早期演示受到材料和界面质量差以及器件组件厚的影响。截止预测频率高于 1 THz 的 HET 的复兴可能与二维材料的到来有关。在这里，我们讨论 HET 工作原理，检查有和没有隧道势垒的 HET 材料架构，并回顾异质结构注意事项。我们讨论了控制势垒和基础性能的材料和界面特性，并批判性地回顾了最近 2D/3D HET 的隧道效率、输出电流密度、电流增益和输出电导。最后，我们概述了与石墨烯形成肖特基势垒的 2D 和 3D 半导体，石墨烯可用作收集器，同时考虑到器件物理和生长问题。