We investigate the quantum-mechanical effects on the electrical properties of the double-gate junctionless field effect transistors. The quantum-mechanical effect, or carrier energy-quantization effects on the threshold voltage, of DG-JLFET are analytically modeled and incorporated in the Duarte et al. model and then verified by TCAD simulation. We investigate the quantum-mechanical effects on the electrical properties of the double-gate junctionless field effect transistors. The quantum-mechanical effect, or carrier energy-quantization effects on the threshold voltage, of DG-JLFETs are analytically modeled and incorporated in the Duarte et al. model and then verified by TCAD simulation.