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