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 exhibit negative resistance. Four of these devices are arranged in a diamond shape in a bridge (-5[1])rectifier. (10[1]-5[1])These devices (-5[1])have an (-5[1])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, 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 (-5[1])and come in a “light-emitting” type. (10[2])■END■ (10[4]0[2])