Development of MEMS Process Compatible (Bi,Sb)2(Se,Te)3-Based Thin Films for Scalable Fabrication of Planar Micro-Thermoelectric Generators

Abstract

Bismuth telluride-based thin films have been investigated as the active material in flexible and micro thermoelectric generators (TEGs) for near room-temperature energy harvesting applications. The latter is a class of compact printed circuit board compatible devices conceptualized for operation at low-temperature gradients to generate power for wireless sensor nodes (WSNs), the fundamental units of the Internet-of-Things (IoT). CMOS and MEMS compatible micro-TEGs require thin films that can be integrated into the fabrication flow without compromising their thermoelectric properties. We present results on the thermoelectric properties of (Bi,Sb)2(Se,Te)3 thin films deposited via thermal evaporation of ternary compound pellets on four-inch SiO2 substrates at room temperature. Thin-film compositions and post-deposition annealing parameters are optimized to achieve power factors of 2.75 mW m−1 K−2 and 0.59 mW m−1 K−2 for p-type and n-type thin films. The measurement setup is optimized to characterize the thin-film properties accurately. Thin-film adhesion is further tested and optimized on several substrates. Successful lift-off of p-type and n-type thin films is completed on the same wafer to create thermocouple patterns as per the target device design proving compatibility with the standard MEMS fabrication process.

Electronic Structure and Transport Properties of Bi2Te3 and Bi2Se3 Single Crystals

“…This, in turn, can be used in various devices. Due to their special surface states, Bi 2 Te 3 and Bi 2 Se 3 have great application potential and are successfully used in spintronic [15][16][17][18] and thermoelectronic [19][20][21][22][23] devices, biological and chemical sensors [24][25][26], and photonic and optoelectric applications [27,28]. Therefore, obtaining new information about the features of the electronic structure and electronic transport in such topological materials is of great interest and is relevant from both fundamental and applied points of view.…”

Microscale Engineering of n-Type Doping in Nanostructured Gallium Antimonide: AC Impedance Spectroscopy Insights on Grain Boundary Characterization and Strategies for Controlled Dopant Distribution

“…The materials synthesized with grain sizes smaller than the typical mean free path of phonons but larger than that of electrons help reduce lattice contributions to thermal conductivity by acting as scattering centers. This meticulous control is particularly significant in the era of miniaturized devices, where material performance and device efficiency correlate with feature sizes and architectures at these scales [ 13 , 14 , 15 ]. Tremendous potential exists in significantly reducing lattice contributions to thermal conductivity while concurrently controlling the Fermi energy through strategic use of dopants, alloying, and nano-sized inclusions [ 16 , 17 , 18 , 19 ].…”