The InGaAs-InAlAs-InP high electron mobility transistor (InP HEMT) is the preferred active device used in a cryogenic low noise amplifier (LNA) for sensitive detection of microwave signals. We have investigated the angular dependence of the InP HEMT when oriented in a magnetic field at 2 K ambient temperature up to 14 T. A sharp angular dependence as a function of the magnetic field was measured for the output current of the InP HEMT. This was accurately described by a geometrical magnetoresistance expression for all angles and magnetic field strengths. Key device parameters such as transconductance and on-resistance were significantly affected at small angles and magnetic fields. The strong angular dependence of the InP HEMT output current in a magnetic field has important implications for the alignment of cryogenic LNAs in microwave detection experiments involving magnetic fields.
This work was performed in GigaHertz Centre in a joint research project between Chalmers University of Technology, Low Noise Factory AB, Wasa Millimeter Wave AB, Omnisys Instruments AB and RISE Research Institutes of Sweden. We are grateful to Serguei Cherednichenko for valuable assistance in the noise measurements and Niklas Wadefalk for the LNA design.