ABSTRACT
This chapter focuses on the core or the engine of a light-emitting diode (LED) lamp, which is a particular type of semiconductor diode that produces light when it is forward biased. An LED is a semiconductor diode that is formed by joining p- and n-type materials together that have large charge carrier concentrations of holes and electrons, respectively. Most white LEDs in the market use blue LED chips made from GaN-based materials and some type of yellow or warm color phosphor coating, placed either directly on the chips or on the polymer or resin encapsulation, or even on the surface of the final enclosure. LED lamps’ efficacy, brightness, color quality and stability depend on many parameters and their interdependencies are quite complex. LED device fabrication involves electrical contact formation, coating, passivation, die bonding and separation, and other processes that make each individual chip suitable for subsequent packaging and testing.
