The light output of the solid state lamp will vary with the current through the lamp. If lamp voltage (forward bias) is increased, the current through the lamp increases. Correspondingly, the light output increases with increased voltage.
The threshold voltage (Point A) is the point at which first light is generated. Point B is the breakdown point with revere bias. Light may be emitted here, but by a different mechanism, known as impact ionization. This is an inefficient mode and can cause destructive heating of the lamp.
The semiconductor with the light-emitting in junction is typically attached to the base of a two leaded header, forming the bottom contact on the n-side. A small metal dot on the p-side forms the top contact. A wire is then connected from the p-side contact to the other terminal to complete the electrical connections. To provide protection to the electrical connections and to produce the desired radiation pattern, a plastic filter is molded into the leads in direct contact with the semiconductor.