Development of thick-film thermoelectric microcoolers using electrochemical deposition

摘要

Advanced thermoelectric microdevices integrated into thermal management packages and low power, electrical source systems are of interest for a veriety of space and terrestrial applications. By shrinking the size of the thermoelements, or legs, of these devices, it becomes possible to handle much higher heat fluxes, as well as operate at much lower currents and higher voltages that are more compatible with electronic components. The miniaturization of state-of-the-art thermoelectric module technology based on Bi_2Te_3 alloys is limited due to mechanical and manufacturing constraints for both leg dimensions (100-200 mu m thick minimum) and the number of legs (100-200 legs maximum). We are investigating the development of novel microdevices combining high thermal conductivity substrate materials such as diamond, thin film metallization and patterning technology, and electrochemical deposition o f thick thermoelectric films. It is anticipated that thermoelectric microcoolers with thousands of thermocopules and capable of pumping more than 200 W/cm~2 over a 30 to 60 K temperature diffrence can be fabricated. In this paper, we report on our progress in developing an electrochemical deposition process for obtaining 10-50 mu m thick films of Bi_2Te_3 and its solid solutions. Results presented here indicate that good quality n-type Bi_2Te_3, n-type Bi_2Te_(2.95)Se+(0.05) and p-type Bi_(0.5)Sb_(1.5)Te_e thick films can be deposited by this technique. Somedetails about the fabication of the miniature thermoelements are also described.