Description: A visible light emitting device includes a wide band gap semiconductor layer doped with one or more elements which emit light at various wavelengths based upon atomic transitions. The semiconductor preferably is GaN, InN, AIN, BN or alloys thereof doped with a lanthanide element such as Er, Pr or Tm. The light emission can be enhanced by annealing the WBGS.
Wide band gap semiconductors (WBGS) doped with light emitting elements such as rare earth elements (RE) and other elements with partially filled inner shells are particularly attractive for LEDs because the emission efficiency appears to increase with band gap value, thus allowing room temperature operation without the need to introduce impurities.
The present invention is premised on the realization that wide band gap semiconductor substrates doped with elements with partially filled inner shells such as rare earth elements and transition metals can be formed and will emit in the visible and ultraviolet spectrum at a wide range of temperatures. The wide band gap semiconductor material are group III-V and IV materials including diamond, GaN, AIN, InN, BN and alloys thereof. These are doped with elements such as cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, turbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium or other elements with partially filled inner shells.
By proper formation of the wide band gap semiconductor material and proper introduction of the rare earth element, a light emitting diode can be formed which emits in the visible spectrum.
By selection of the appropriate dopant material, one can select the appropriate color. For example, in GaN, erbium will produce green whereas thulium will produce blue and praseodymium will produce red.|
US Pat. No. 6,255,669, "Visible light emitting device formed from wide band gap semiconductor doped with a rare earth element" And
US Pat. No. 6,406,930, "Fabrication of visible light emitting device formed from wide band gap semiconductor doped with a rare earth element"
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