Cryogenic GaAs high-electron-mobility-transistor amplifier for current noise measurements

We show that a cryogenic amplifier composed of a homemade GaAs high-electron-mobility transistor (HEMT) is suitable for current-noise measurements in a mesoscopic device at dilution-refrigerator temperatures. The lower noise characteristics of our homemade HEMT lead to a lower noise floor in the experimental setup and enable more efficient current-noise measurement than is available with a commercial HEMT. We present the dc transport properties of the HEMT and the gain and noise characteristics of the amplifier. With the amplifier employed for current-noise measurements in a quantum point contact, we demonstrate the high resolution of the measurement setup by comparing it with that of the conventional one using a commercial HEMT.

Automated summary

This study demonstrates the suitability of a homemade GaAs HEMT amplifier for current-noise measurements in mesoscopic devices at dilution-refrigerator temperatures. The lower noise characteristics of the homemade HEMT allow for a lower noise floor in the experimental setup and more efficient current-noise measurement compared to commercial HEMTs. The high resolution of the measurement setup is showcased by comparing it with a conventional one using a commercial HEMT.