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 (-5[1])(“eh-SAH-key”) to exhibit (10[1])negative resistance. Four of these devices are arranged in a diamond shape in a bridge rectifier. (10[1]-5[1])These devices have an exponential I-V (“eye-vee”) relationship according to the Shockley equation. (10[1])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 these circuit elements that only let current flow in one direction and come in a “light-emitting” type. (10[2])■END■ (10[1])