High temperature (T > 300 K) light emitting diodes for 8-12 μm spectral range

Contrary to conventional light emitting diodes for visible and very near infrared utilizing interband ((h) over bar omega > E-g) luminescence, the longer infrared emitting diodes (LIREDs) we describe here utilize intraband ((h) over bar omega < E-g) electron transitions and emit beyond the fundamental absorption range of the material used. Made of indirect band gap semiconductors (like Ge, Si) and, therefore, free from the Auger recombination impact, LIREDs efficiently operate at higher temperatures (T > 300 K) in the longer wavelength atmospheric window (8-12 mum). Electrically modulated power emitted is comparable to that for black body sources whereas shorter rise-fall times are due to recombination processes (similar to 200 mus) and not dependent on pixel thermal mass and thermal conduction. LIREDs can be made of different semiconductor structures provided the controllable modulation of free carrier concentration in the device base is achieved. The main parameters of Ge based LIREDs under injection mode are reported. (C) 2000 Elsevier Science B.V. All rights reserved.