A planar Bi-Sb multijunction thermal converter with small ac-dc transfer differences

Author

Kim, Jin-Sup ; Lee, Hyun-Cheol ; Lee, Jong-Hyun ; Lee, Jung-Hee ; Park, Se Il ; Kwon, Sung-Won

Author_Institution

Sch. of Electron. & Telecommun. Eng., Inje Univ., Kimhae, South Korea

Volume

51

Issue

1

fYear

2002

fDate

2/1/2002 12:00:00 AM

Firstpage

115

Lastpage

119

Abstract

A planar Bi-Sb multijunction thermal converter was fabricated on the LPCVD Si₃N₄/SiO₂/Si₃N ₄-diaphragm, prepared by silicon bulk micromachining, which thermally isolated a bifilar Pt- or NiCr-heater and the hot junctions of a Bi-Sb thermopile from the silicon substrate. The voltage responsivity, the ac-dc transfer difference, and the fluctuations of the output thermoelectric voltage and heater resistance were discussed to investigate the design factors of a thermal converter. The respective voltage responsivities in air and in a vacuum of the thermal converter with a built-in NiCr-heater were about 14.0 mV/mW and 54.0 mV/mW. The ac-dc voltage and the current transfer differences in air were about ±0.60 ppm and ±0.11 ppm in the dc reversing frequency range from 10 Hz to 10 kHz. They are sufficiently small to be used as practical ac standards. Compared to the thermal converter with a built-in Pt-heater, the thermal converter with a built-in NiCr-heater demonstrated a higher voltage responsivity and smaller ac-dc transfer differences, while exhibiting slightly larger fluctuations in output thermoelectric voltage and in heater resistance

Keywords

antimony; bismuth; convertors; elemental semiconductors; measurement standards; silicon; silicon compounds; thermopiles; transducers; 10 Hz to 10 kHz; AC-DC difference; Bi-Sb thermopile; BiSb; FRDC; LPCVD; NiCr; NiCr-heater; Pt; Pt- NiCr-heater; Si; Si substrate; Si₃N₄-SiO₂-Si₃N₄; Si₃N₄/SiO₂/Si₃N₄-diaphragm; fluctuations; output thermoelectric voltage; planar Bi-Sb multijunction thermal converter; thermal converter; thermoelectric voltage; voltage responsivity; Analog-digital conversion; Fluctuations; Heat transfer; Micromachining; Resistance heating; Silicon; Thermal factors; Thermal resistance; Thermoelectricity; Voltage;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.989913

Filename

989913