LED MATERIALS

Sapphire Research and Production Amalgamation in Moscow demonstrated the first SiC blue light-emitting diode, and has continued to do considerable research and development in SiC light emitters. An experimental blue LED operating at 480 nm with a 2 candela maximum output and a green LED at 520 nm with 3- 4 candela output were demonstrated. Dr. Sushkov described an ultraviolet SiC LED operating at 410 nm. He suggested that such an LED could be used to stimulate emission from a phosphor. The efficiency of the UV LED is very low, but the effect was observable.

Presently, Sapphire manufactures a broad range of incoherent light-emitting devices. The scientists' work in III-V semiconductors includes GaAs, AlGaAs, GaAsP, and other quaternary compounds. The approach is to buy wafer material from other suppliers that grow epitaxial structures and heterojunctions by LPE, VPE, and MBE, and then do all of the device processing and packaging. Standard semiconductor processing capabilities are available, including photolithography, ion implantation, coatings, and metallization. The colors available are red (AlGaP, GaAlAs), green (520 nm, GaP), and blue (480 nm, SiC). The production equipment is almost completely from the FSU and other former Warsaw Pact countries. Substrates, chemicals, and materials are obtained from the Research Institute of Materials Science and the Research Institute for Electronic Materials.

The Positron Research and Manufacturing Corporation in St. Petersburg produces optoelectronic devices, discrete devices, high-temperature FETs, thyristors, and integrated circuits (ICs) for optoelectronic and high-temperature applications. Devices are made from GaAs, GaAlAs, and GaP. One GaAs device for commutation applications switches at 100 psec. The corporation claims to have high efficiency, narrow spectral distribution LEDs for use in transmitters and receivers, which are used for television remote control devices, indicators, alarm systems, and for taking measurements during machining applications.

In the Department of Optoelectronics, Institute of Semiconductors, Ukraine Academy of Sciences, light-emitting structures and photodetectors based on III-V semiconductors are studied. Amorphous SiC structures deposited onto flexible substrates have been developed recently.


Published: December 1994; WTEC Hyper-Librarian