UCSB first blue LED longer (30-3-1) surface nitride substrate

University of California at Santa Barbara (UCSB) researchers recently reported the first package of high power, high efficiency semi polar (30-3-1) blue LED (452nm), please refer to Ingrid L. related articles published in the Japanese Journal of Koslow Applied Vol p080203 Physics journal in 2010 49, the. Since last year, UCSB has begun to study the growth of LED and lasers in a number of different semi polar crystals in the hope of achieving better performance than conventional C devices.

The external quantum efficiency (EQE) of the C device can reach about 60%, which seems to be difficult to be surpassed. This is also the advantage of mature technology, the growth of other crystalline materials is still in a relatively early stage, which means that these materials than on the C surface growth of the material generally have a higher defect density (about 1010 /cm). However, C surface devices to get such a high EQE value, it requires a very special working conditions, such as special current and temperature control, etc.. What we really need is to be able to work under a variety of conditions and achieve high efficiency and high power.

Semi polar and polar materials are believed to produce better devices because of the small electric field in the active region. In polar devices, the electric field can cause the quantum confined Stark effect (Quantum-confined Starker, Effect, QCSE), the separation of electrons and holes, so the radiation process of composite and other mechanisms than needs longer time, the luminous efficiency is reduced. The electric field is derived from the spontaneous polarization and piezoelectric polarization of the nitride semiconductor material.

UCSB researchers said they used in recent experiments (30-3-1) crystal plane and (20-21) only 5 degrees difference between the crystal surface, which is the latest development of the Japanese Sumitomo Electric green laser performance is expected