Semiconductor materials have a very interesting feature, is the so-called carrier; carrier is divided into two categories: one for the electronic, with negative; the other for the hole, with positive electricity. LCD light principle is the use of two carriers in some conditions can be combined, the release of energy in the form of photons released and light.
And therefore, according to the different materials, electrons and holes occupied by the energy level is different, that is, the relative energy level of electrons and holes is the difference between the two carriers to determine the level of energy, can produce a different Energy of the photon, which can control the LED emitted by the wavelength of light, that is, the spectrum or color.
Most of the applications, LED are super-DC way, it has the following characteristics:
Bias characteristic: When the DC has enough positive voltage, the LED current will rise rapidly, and this access to the current is called "along the current", and the voltage across the LED is called " Voltage". If the voltage range is high or low that is abnormal quality, and usually the shorter the wavelength of the LED will be the higher the voltage.
Reverse bias characteristics: As the name suggests is to give LED negative voltage, also known as "leakage voltage", in general, different LED materials will have their own reasonable voltage, and cause reverse voltage characteristics of the reasons for the electrostatic discharge, this Features can also be used to evaluate the quality of this LED.