Nanolithographic Process Precisely Produces Reliable Quantum Dot Active Layers for LEDs at Lower Costs

The light emitting diode (LED) is a kind of semiconductor component. Compared to the general light bulb, the service life of the LED is longer than that  by 50 to 100 times; the power consumption of the LED is only 1/3.about.1/5 that of the general light bulb. Owing to the many advantages of LEDs as a lighting source, it will probably dominate the future lighting market. It will become a new lighting source with benefits in energy savings and environmental protection and will eventually replace conventional tungsten and mercury lighting sources in 21st century.  The world lighting market is believed to exceed $71 billion annually. 
Ming-Nung Lin (Pingtung City, Pingtung County, TW) garnered U.S. Patent 7,659,129 for an efficient method for manufacturing quantum dot active layers for LEDs by nano-lithography.”  Nano-lithography permits fabrication of new active layers of LEDs with a nano quantum dot structure in a more miniature, reliable and precise manner than that permitted by current fabrication methods.  The LEDs resulting from nano-lithography are high quality and feature longer light wavelengths, brighter luminance and lower forward bias voltage.   .
The dimensional size of each nano quantum dot and the respective distance among all the nano quantum dots can be completely controlled in 100% precise manner so that the performance and the optical properties are very stable.  The process can be further employed to create an effective and reliable montage effect as well as considerably improve various LED photoelectrical effects The fabrication method “is very valuable” in industrial applications,” says Lin.
Lin ‘s fabrication method for quantum dot active layer of LED by nano-lithography” includes  the process steps:
(a): Firstly, deposit a sealant of gas molecule or atom state on top-opening of a nano cylindrical pore on an epitaxy substrate so that the diameter of top-opening gradually reduce to become a reduced nano-aperture, whose opening diameter is smaller than that of the top-opening;
(b): Secondly, firmly place the epitaxy substrate on a tilt-rotary console having capability of 3-D tilt with rotation in horizontal direction and directly pass a deposit material of gas molecule or atom state perpendicularly through the reduced nano-aperture so that a nano quantum dot of nano structure with diameter being same as that of the reduced nano-aperture is directly formed on the surface of the epitaxy substrate, which being laid beneath the bottom of the nano cylindrical pore;
 (c): Thirdly, tilt rightwards the epitaxy substrate together with the tilt-rotary console in a right tilt angle by the reduced nano-aperture as center and re-pass the deposit material of gas molecule or atom state through the reduced nano-aperture in same direction as the previous direction so that another nano quantum dot of nano structure with diameter being same as that of the reduced nano-aperture is directly formed on the surface of the epitaxy substrate with position at right side of the previous nano quantum dot;
d): Fourthly, tilt leftwards the epitaxy substrate together with the tilt-rotary console in a left tilt angle by the reduced nano-aperture as center and re-pass the deposit material of gas molecule or atom state through the reduced nano-aperture in same direction as the previous direction so that another nano quantum dot of nano structure with diameter being same as that of the reduced nano-aperture is directly formed on the surface of the epitaxy substrate with position at left side of the previous nano quantum dot;
 (e): Fifthly, properly rotate the epitaxy substrate together with the tilt-rotary console in a rotation angle by the reduced nano-aperture as center and re-pass the deposit material of gas molecule or atom state through the reduced nano-aperture in same direction as the previous direction so that a further nano quantum dot of nano structure with diameter being same as that of the reduced nano-aperture is directly formed on the surface of the epitaxy substrate with position at front side of the previous nano quantum dot;
(f): Finally, by means of solution rinsing (i.e. wet etching) or gas etching (i.e. dry etching), remove all the nano cylindrical pores on the epitaxy substrate, many active layers of nano quantum dots in same dimension for the LED are fabricated on the epitaxy substrate in high density and even distribution manner.