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.
