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_xGa_1-xAs 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 1.4×10^-4 K^-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^*=6.9×10⁸ cm√(Hz)/W which compare to the predicted performance