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ABSTRACT: The experimental characterization of single barrier heterostructure thermionic cooling devices at cryogenic temperatures is
reported. The device studied was a cylindrical InGaAs microrefrigerator, in which the active layer was a 1μm thick In0.527Al0.218Ga0.255As heterostructure barrier with n-type doping concentration of 6.68×1016cm−3 and an In0.53Ga0.47As emitter/collector of 5×1018cm−3
n-doping. A full field thermoreflectance imaging technique was used to measure the distribution of temperature change on the
device’s top surface when different current excitation values were applied. By reversing the current direction, we studied
the device’s behavior in both cooling and heating regimes. At an ambient temperature of 100K, a maximum cooling of 0.6K
was measured. This value was approximately one-third of the measured maximum cooling value at room temperature (1.8K). The
paper describes the device’s structure and the first reported thermal imaging at cryogenic temperatures using the thermoreflectance
technique.
Journal of Electronic Materials 04/2012; 38(7):1309-1314. · 1.47 Impact Factor
