In recent years, the concept of Internet-of-Things (IoT) has attracted significant interests. Required by the applications, the IoT power optimization has become the key concern, which relies on innovations from all levels of device, circuits, and architectures. Meanwhile, the energy efficiency of existing IoT implementations based on the CMOS technology is fundamentally limited by the device physics and also the circuits and systems built on it. This chapter focuses on a different dimension, exploring how emerging beyond-CMOS devices, such as tunnel field effect transistor (TFET) and negative capacitance FET (NCFET), and the circuits and architectures built upon them, could extend the low-power design space to enable IoT applications with beyond-CMOS features.