Angular Dependence of InP High Electron Mobility Transistors for Cryogenic Low Noise Amplifiers under a Magnetic Field

This work addresses the angular dependence of DC properties in InP HEMT devices under the influence of applied static magnetic field at 2 K. When kept at an angle 90 degrees towards a magnetic field of 14 T, the maximum output drain current Ids was reduced drastically. A rotation sweep of the transistor revealed a strong angular and B-field dependence on Ids. This was correlated with a reduction in dc transconductance and increase in on-resistance of the transistor. The RF properties of the transistor were tested by measuring an 0.3-14 GHz InP HEMT MMIC low-noise amplifier (LNA) at 2 K kept at an angle 90 degrees towards a magnetic field up to 10 T. The gain and noise temperature were strongly decreased and increased, respectively, already below 1 T. The results show that precise alignment of the cryogenic InP HEMT LNA is crucial in a magnetic field. Even a slight mis-orientation of a few degrees leads to a strong degradation of the gain and noise temperature. ain and noise temperature.