The two-dimensional bigradient effect and its application for GHz-THz sensing

A well-pronounced asymmetry in I-V-characteristics within low, 4.2-80 K, temperatures is demonstrated in asymmetrically in-plane shaped modulation-doped GaAs/AlGaAs structures. The results are explained by the presence of two different electric field gradients - the bigradient effect - induced by the geometrical shape. The features of the effect are revealed; the possibility to use it for GHz-THz sensing is explored via development of asymmetrically-shaped GaAs/Al0.3Ga0.7As-based and In0.54Ga0.46As-based bow-tie diodes. An effective bandwidth of 10 GHz - 1 THz and a sensitivity of about 5-6 V/W is achieved at room temperature.