Ultra-low-temperature cooling of two-dimensional electron gas

A new design has been used for cooling GaAs/AlxGa1-xAs sample to ultra-low-temperatures. The sample, with electrical contacts directly soldered to the sintered silver powder heat exchangers, was immersed in liquid He-3, which was cooled by a PrNI5 nuclear refrigerator. The data analysis shows that the two-dimensional electron gas (2DEG) was cooled to 4.0 mK at the refrigerator base temperature T-b of 2.0 mK. The design with heat exchanger cooling is applicable to any ultra-low-temperature transport measurements of 2DEG system. (C) 2000 Published by Elsevier Science B.V. All rights reserved.