Nanomaterials - 14

Abstract

Ge is expected to exhibit significant thermoelectric performance at ambient temperatures due to its narrow band gap. Furthermore, its low crystallization temperature positions it as a promising candidate for flexible thermoelectric devices. Recently, we have focused on the precursor deposition temperature while advancing the solid phase crystallization (SPC) of Ge, thereby achieving a notable enhancement in the mobility of Ge thin films [1,2]. Utilizing SPC, we have attained a world-leading power factor (PF) for Ge thin films through controlled dopant concentration using diffusion agents [3]. Nevertheless, the activation of dopants at low temperatures remains challenging, impeding the achievement of superior electrical and thermoelectric properties below the thermal resistance threshold of plastics (<500°C). Addressing these issues, our research has enhanced the electrical characteristics of Ge, achieving unparalleled electron mobility by co-doping n-type dopants on germanium, as shown in previous studies [1,4,5].
 In this study, we investigate the physical properties of Ga-doped Ge thin films synthesized via co-doping, and measure the thermoelectric properties of both P-doped Ge and Ga-doped Ge thin films. Achieved at synthesis temperatures below the thermal resistance of plastics, the highest PF for a group IV material was attained.