Embodiments of the disclosure provide an integrated circuit (IC) structure with a high impedance semiconductor material between a substrate and transistor. The IC structure may include: a substrate, a high impedance semiconductor material on a portion of the substrate, and a transistor on a top surface of the high impedance semiconductor material. The transistor includes a semiconductor channel region horizontally between a first source/drain (S/D) region and a second S/D region. The high impedance semiconductor material is vertically between the transistor and the substrate; a first insulator region is on the substrate and horizontally adjacent the first S/D region; and a first doped well is on the substrate and horizontally adjacent the first insulator region. The first insulator region is horizontally between the first doped well and the transistor.