A class of these circuit elements called transferred electron devices are used in oscillators to produce microwaves. Quantum tunneling allows a class of these devices named for Leo Esaki (“eh-SAH-key”) to (10[1])exhibit (-5[1])negative resistance. (10[1])Four of these devices are arranged in a diamond shape (-5[1])in a (-5[1])bridge rectifier. (-5[1])These devices have an exponential I-V (“eye-vee”) relationship (10[1])according to the Shockley equation. Past the breakdown voltage, these devices can conduct in both directions. On circuit diagrams, these devices are represented by a triangle touching a line. For 10 points, name (10[1])these circuit elements (10[1])that only let current flow in one direction (10[1])and come in a “light-emitting” type. ■END■ (10[2])