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.