51.3 Why must we study physics MOSFET Quantum well Gate n-doped GaAS GaAs GaAs -type -type AIGA p-type layer Induced channel ith n-carriers(b) Metal-oxide semiconductor The moving field-effect transistor range of electrons is 20 nanometers 81.3 Why must we study physics @Physics and optics information technology Signal source -laser based on the quantum physics Transmission medium material(optical fiber, disk) based on physIcs Detection and treatment of the information technologies of optical acoustics, optical magnetism, optical electronics, integrated optics∴…, all based on physics.13 §1.3 Why must we study physics MOSFET Quantum well Metal-oxide semiconductor field-effect transistor The moving range of electrons is 20 nanometers §1.3 Why must we study physics 4Physics and optics information technology Signal source —laser based on the quantum physics Transmission medium --material (optical fiber, disk)based on physics Detection and treatment of the information --technologies of optical acoustics, optical magnetism, optical electronics, integrated optics ……, all based on physics