From a fully ballistic FET to ultra-low noise cryogenic HEMTs

Orateur : Yong JIN (LPN)

Based on AlGaAs/GaAs heterojunction, a 2DEG (Two dimensional Electron Gas) with high electron mobility at low temperature can be obtained and used to investigat e quantum transports of electrons at low temperature in mesoscopic physics. Beyond the basic research, we used a 2DEG and the QPC (Quantum Point Contact) configuration to demonstrate a fully ballistic FET (Field-Effect Transistor) at 4.2 K and the experimental result is confirmed by the simulation, using Landauer-Buttiker formalism from the mesoscopic physics. The know-how in mesoscopic devices and ballistic FET under cryogenic conditions allowed us to realize specific cryogenic HEMTs (High Electron Mobility Transistors) and to decrease their noise voltage and noise current to the range of sub-nV/Hz1/2 and of aA/Hz1/2, respectively. Indeed, these HEMTs are in the process of filling a gap in high impedance and low-frequency deep cryogenic readout electronics and few applications will be shown.

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