Free-standing AlGaAs thermopiles for improved infrared sensor design

Our group introduced the GaAs/AlGaAs material system for various integrated and micromachined thermoelectric sensors [1]-[6]. Investigating the material parameters of AlxGa1-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 x 10(-4) K-1 are predicted. Simultaneously, this material is compatible for micromachining 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 x 10(8) cm root Hz/W which compare to the predicted performance.