Review of polysilicon thermoelectric energy generators

Abstract

Among the power generation for micro sensor and actuator in wireless sensor network (WSN), Internet of Things (IoT), and wearable devices applications, thermoelectric energy generators (TEGs) that can convert body heat into electricity without moving parts is considered most promising. With the advent of foundry services in IC industry over the past two decades, standard CMOS/BiCMOS process for microprocessors and micro actuators/sensors can be applied as a perfect platform for semiconductor TEGs. Many TEG designs have therefore adopted the mature, reliable, and high yield process, where the polysilicon layers facilitate high integration density of thermocouples on a wafer. This review aims at summarizing the progress of semiconductor TEGs from tailored MEMS process to commercially available standard CMOS/BiCMOS process. By comparing the reports in the open literature, semiconductor TEGs are shown to achieve performance competitive to the bismuth telluride (BiTe)-based TEGs. The performance of a semiconductor TEG can be improved by exploiting configuration design, thermocouple dimension and materials properties in modern silicon processing technology. State-of-the-art polysilicon TEGs have been shown to achieve power factor about 10 -1 ∼10 -2 μW/cm 2 K 2 and voltage factor 10 1 ∼10 2 V/cm 2 K. A 5 × 5 mm 2 TEG chip is capable of delivering more than 3 μW and over 3 V when operating at 10 K temperature difference in body temperature range.