LED development path
Electro-luminescence in inorganic materials is the basis of LED luminescence. LED luminescence was reported by Henry Round and Oleg Vladimirovich Losev in 1907 and 1927, respectively, by the current shining through the silicon carbide (SiC) crystals. These results lead to further theoretical studies of the semiconductor and p-n junction photovoltaic processes.
In the 1950s and 1960s, scientists began to study the electroluminescent properties of Ge, Si and a series of III-V semiconductors such as InGaP and GaAlAs. Richard Haynes and William Shockley demonstrated that recombination of electrons and holes in a p-n junction leads to luminescence. Subsequently, a series of semiconductors were studied, culminating in the first red LED developed by Nick Holonyak in 1962. Under his influence, George Craford invented orange light LEDs in 1971, and in 1972, he invented yellow and green LEDs, each consists of GaAsP..
Strong research has rapidly commercialized LEDs that emit light over a wide range of wavelengths (from infrared to yellow)， and Mainly used for telephone or control panel lights. In fact, these LEDs are inefficient and have limited current densities that make them very low-brightness and not suitable for general lighting.