Magnetic field influence on detection properties of planar microwave diodes on the base of modulation doped semiconductor structures

Detection properties of planar microwave diodes have been investigated under the action of external magnetic field at room temperature. The diodes were fabricated from modulation doped semiconductor structures having planar asymmetrically and symmetrically narrowed n-n+ junctions. Their operation is based on non-homogeneous carrier heating by a microwave electric field. Frequency dependence of the detected voltage confirmed presence of rectification of microwave currents in the signal formation. Experimental investigations revealed that voltage sensitivity of the diodes was conditioned by the external magnetic field. Sensitivity changes are explained as a result of the magnetic field influence on rectification of microwave currents as well as taking into account the influence of magnetoresistance effect on the formation of the detected voltage. The magnetoresistance is manifested more strongly, when magnetic field is perpendicular to the longitudinal axis of the diode owing to more influence of Lorentz force. Demonstration of magnetoresistance at magnetic field, which is parallel the diode axis, is explained by the fact, that currents in the asymmetrically necked diode make a non-zero angle with lines of electric and magnetic fields owing to widening of n field of n-n⁺ junction. When this angle between lines of electrical and magnetic fields decreases, that occurs in case of the symmetrically necked diode, the more weak averaged relative voltage sensitivity of diodes is experimentally observed.