Semiconductor color-tunable broadband light sources and full-color microdisplays
– HW Choi, KN Hui and X Wang
Publication Date: 2011
Patent Office: US
Patent Number: US 7,982,228
Methods and systems are provided that may be used to utilize and manufacture a light sources apparatus. A first light emitting diode emits light having a first wavelength, and a second light emitting diode for emitting light having a second wavelength. Each of the first and second light emitting diodes may comprise angled facets to reflect incident light in a direct toward a top end of the first light emitting diode. The second light emitting diode comprising angled facets may reflect incident light in a direction toward a top end of the second light emitting diode. A first distributed Bragg reflector is disposed between the top end of the first light emitting diode and a bottom end of the second light emitting diode to allow light from the first light emitting diode to pass through and to reflect light from the second light emitting diode.
Chip stacking
– HW Choi
Publication Date: 2012
Patent Office: US
Patent Number: US Patent Application 2012/0292788
Methods and systems are provided to utilize and manufacture a stacked chip assembly. Microelectronic or optoelectronic chips of any dimensions are directly stacked onto each other. The chips can be of substantially identical sizes. To enable forming the stacked chip assembly, trenches are laser micro-machined onto the bottom surface of a chip to accommodate the bond wedge/ball and wire path of the chip beneath it. Consequently, chips can be tightly integrated without a gap and without having to reserve space for the bond wedges/balls.
Light-emitting diodes (LEDs) with monolithically-integrated photodetectors for in situ real-time intensity monitoring
– HW Choi, KH Li, and H Lu
Publication Date: 2019
Patent Office: US
Patent Number: US Patent Application 2019/0157508
A device includes a light-emitting diode (LED) integrated with a photodetector on the same semiconductor platform, such that the photocurrent generated by the photodetector can be used to monitor the optical output of the LED, which is located adjacent to the photodetector. The device provides a compact, robust, reliable and low-cost way of monitoring LED emission.
White nanoLED without requiring color conversion
– HW Choi
Publication Date: 2016
Patent Office: US
Patent Number: US 9,401,453
A nano-LED containing an array of nano-pillars of different diameters that are distributed over an emission area of an LED chip is capable of emitting broadband and white or nearly white light. Since each pillar emits light at a different wavelength according to its diameter and strain state, the overall emission spectral characteristics of the device is a combination of individual spectrum, giving rise to broadband emission. The spectral shape can be tailored for different shades of white emission, by controlling the distribution of the different diameter nano-pillars. The nano-pillars are patterned by nanosphere lithography.
Method of making white light LEDs and continuously color tunable LEDs
– HW Choi
Publication Date: 2009
Patent Office: CN
Patent Number: CN 101496188
A light emitting diode comprising of a fluorescent microsphere coating is proposed. The coating consists of fluorescent microspheres which fluoresce at green and red wavelengths, excited by a shorter wavelength LED. Due to the micron-scale dimension of the spheres, they are non-resolvable to the human eye and the overall optical output appears as color mixed. By varying the proportions of green and red fluorescent microspheres and the wavelength of the excitation source, the color of the optical output can be tuned. If the optical output has of blue, green and red components in the correct proportions, white color emission can be achieved. The light emitting diode can be sectioned into multiple individually-addressable regions. Each section can emit at a different wavelength according to the type of fluorescent microspheres coated. By varying the intensity of the blue, green and red regions by changing the bias Voltage, the output wavelength (color) can be continuously tuned(varied).
MicroLED
– MD Dawson, HW Choi and CW Jeon
Publication Date: 2009
Patent Office: US
Patent Number: US 7,598,149
An array of light emitting devices, each device comprising a sloped wall mesa (24) of luminescent semiconductor material. Extending over the sloped wall mesas (24) is a metal contact (30). The array can be arranged as a parallel addressable system so that all devices (24) can be stimulated to emit light simultaneously. Alternatively, the array can be arranged as a matrix addressable array, in which case individual devices can be selectively stimulated.