A Survey Describing Beyond Si Transistors and Exploring Their Implications for Future Processors

The advancement of Silicon CMOS technology has led information technology innovation for decades. However, scaling transistors down according to Moore's law is almost reaching its limitations. To improve system performance, cost, and energy efficiency, vertical-optimization in multiple layers of the computing stack is required. Technological awareness in terms of devices and circuits could enable informed system-level decisions. For example, graphene is a promising material for extremely scaled high-speed transistors because of its remarkably high mobility, but it can not be used in integrated circuits as a result of the high leakage current from its zero bandgap. In this article, we discuss the fundamental physics of transistors and their ramifications on system design to assist device-level technology consideration during system design. Additionally, various emerging devices and their utilization on a vertically-optimized computing stack are introduced. This article serves as a survey of emerging device technologies that may be relevant in these areas, with an emphasis on making the descriptions approachable by system and software designers to understand the potential solutions. A basic vocabulary will be built to understand how to digest technical content, followed by a survey of devices, and finally a discussion of the implications for future processing systems.