Free-standing AlGaAs thermopiles for improved infrared sensor design

Our group introduced the GaAs/AlGaAs material system for various integrated and micromachined thermoelectric sensors. Investigating the material parameters of Al/sub x/Ga/sub 1-x/As in detail indicates that this material system can be optimized with respect to thermoelectric properties. We demonstrate that figures of merit Z as high as 1.4/spl times/10/sup -4/ K/sup -1/ are predicted. Simultaneously, this material is compatible for micro-machining purposes. The presented infrared sensor is optimized with respect to the material parameter and design. The sensors do not need a supporting membrane and hence undesirable parallel thermal conductance is reduced. Sensors of different geometrical dimensions have been fabricated and compared. Black body measurements result in responsivities up to R=365 V/W and maximum relative detectivities of D/sup */=6.9/spl times/10/sup 8/ cm/spl radic/(Hz)/W which compare to the predicted performance.

[1]  Henry Baltes,et al.  Thermoelectric infrared sensors in CMOS technology , 1993 .

[2]  D. Rossberg.  Optical Properties Of The Integrated Infrared Sensor , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[3]  H. Hartnagel,et al.  A piezoresistive GaAs pressure sensor with GaAs/AlGaAs membrane technology , 1995 .

[4]  K. Wise,et al.  A silicon-thermopile-based infrared sensing array for use in automated manufacturing , 1986, IEEE Transactions on Electron Devices.

[5]  Hardness, internal stress and fracture toughness of epitaxial AlxGa1-xAs films , 1994 .

[6]  J. Brice,et al.  Inhomogeneities in the electrical properties of gallium arsenide crystals , 1966 .

[7]  Shlomo Hava,et al.  Thermoelectric properties of Ga1−xAlxAs , 1985 .

[8]  F. Völklein,et al.  High-sensitivity radiation thermopiles made of BiSbTe films , 1991 .

[9]  A. Peczalski,et al.  Analysis of noise margin and speed of GaAs MESFET DCFL using UM-SPICE , 1986, IEEE Transactions on Electron Devices.

[10]  G. R. Lahiji,et al.  A batch-fabricated silicon thermopile infrared detector , 1982, IEEE Transactions on Electron Devices.

[11]  S. Adachi.  GaAs, AlAs, and AlxGa1−xAs: Material parameters for use in research and device applications , 1985 .

[12]  Hans L. Hartnagel,et al.  Infrared thermopile sensor based on AlGaAs—GasAs micromachining , 1995 .

[13]  Viktor Krozer,et al.  Integrated microwave power sensor , 1995 .

[14]  Jianmin Miao,et al.  Fabrication of microstructures for integrated sensors on GaAs , 1993 .

[15]  Kensall D. Wise,et al.  A Bulk-micromachined 1024-element Uncooled Infrared Imager , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[16]  Jan Söderkvist,et al.  Gallium arsenide as a mechanical material , 1994 .

[17]  H. Baltes,et al.  Optimization tool for the performance parameters of thermoelectric microsensors , 1993 .

[18]  J. Wurfl,et al.  Micromechanically Structurized Sensors on GaAs: An Integrated Anemometer , 1992, ESSDERC '92: 22nd European Solid State Device Research conference.

[19]  K. Fricke,et al.  A micromachined mass-flow sensor with integrated electronics on GaAs , 1994 .

[20]  Inspec.  Properties of gallium arsenide , 1986 .

[21]  M. Schulze,et al.  Infrared thermopile sensors with high sensitivity and very low temperature coefficient , 1995 .