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Semipolar-Based Yellow, Green, Blue LEDs with Improved Performance
Technology Benefits
Growth of thicker quantum wellsReduced polarization fields in the device structureReduced defect formation in the active layerLonger wavelength emission
Technology Application
Green, yellow, and blue GaN based light emitting diodesLaser diodesMulti-junction solar cells
Detailed Technology Description
Researchers at the University of California, Santa Barbara have developed a novel approach to reducing or possibly eliminating the polarization effects in GaN-based optoelectronic devices. This approach includes growing the devices on semipolar planes of the crystal. Using semipolar planes instead of c-plane nitrides will reduce total polarization, and there may even be zero polarization for specific alloy compositions. Reducing the polarization field allows for the growth of thicker quantum wells. With thicker quantum wells, higher Indium composition and thus longer wavelength emission can be achieved. The novel approach allows for the fabrication of blue, green, and yellow LEDs on semipolar (Al, In, Ga, B)N semiconductor crystals.
Supplementary Information
Patent Number: US8148713B2 Application Number: US2009419119A Inventor: Sato, Hitoshi | Hirasawa, Hirohiko | Chung, Roy B. | DenBaars, Steven P. | Speck, James S. | Nakamura, Shuji Priority Date: 4 Apr 2008 Priority Number: US8148713B2 Application Date: 6 Apr 2009 Publication Date: 3 Apr 2012 IPC Current: H01L002906 | H01L003302 | H01L003332 US Class: 257013 | 257014 | 257090 | 257E21002 | 257E33002 | 438028 | 977755 Assignee Applicant: The Regents of the University of California Title: Method for fabrication of semipolar (Al, In, Ga, B)N based light emitting diodes Usefulness: Method for fabrication of semipolar (Al, In, Ga, B)N based light emitting diodes Summary: The yellow, amber or red LED is useful in a multi-color LED device, where the semipolar yellow LED is useful in a white LED device (all claimed) and the multi-color LED device is useful in electronic and optoelectronic devices. Novelty: Yellow, amber or red LED useful in a multi-color LED device, comprises an active layer for emitting light, where the active layer is comprised of indium containing single or multi-quantum well structures
Industry
Electronics
Sub Group
Display
Application No.
8148713
Others
Background
Conventional nitride technology for electronic and optoelectronic devices employs nitride films grown along the polar c-direction. However, conventional structures in III-nitride based optoelectronic and electronic devices suffer from the undesirable quantum-confined Stark effect (QCSE), due to the existence of strong piezoelectric and spontaneous polarizations. One approach to eliminating the polarization effects in devices is to grow the devices on nonpolar planes of the crystal. Unfortunately, growth on nonpolar nitrides remains challenging and has not yet been widely adopted in the III-nitride industry.
