Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Heterojunction
Reexamination Certificate
1997-11-19
2001-05-22
Jackson, Jr., Jerome (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Heterojunction
C257S011000, C257S017000, C257S079000, C257S103000
Reexamination Certificate
active
06236060
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of art to which this invention relates is light emitting structures. Specifically, the present invention relates to light emitting structures in back-end of line silicon technology.
2. Description of the Related Art
Most group IV elements and their compounds are poor optical emitters. Optically pumped efficient emission has been shown in porous-silicon (a matrix of quantum-wires formed through electro-oxidation in Hydrofluoric acid) over a considerable period of time although it has suffered from rapid degradation. To date, unstable optically-pumped emission has been achieved in porous silicon and this emission is believed to be caused by multidimensional confinement in nano-structures as well as by defects at surfaces. Photoluminescence has also been observed in silicon nano-particles and silicon implanted in silicon dioxide. Both a certain nano-particle size and a surface termination are needed simultaneously to achieve luminescence at a reasonable efficiency. Harnessing these properties to achieve stable electro-luminescence is of considerable interest as a means of achieving opto-electronic integration in silicon.
For the above reasons, there is a need in the art for a light emitting structure which is stable over a period of time and which can be practiced in back-end of line silicon technology.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a group IV element light emitting structure which is stable over a period of time.
Another object of the present invention is to improve optical emission properties of group IV elements.
Another object of the present invention is to provide a light emitting structure which can be practiced in back-end of line silicon technology.
Yet still another object of the present invention is to provide a group IV element light emitting structure which is easily fabricated.
The present invention provides light emitting structures using group IV elements such as silicon, germanium, and GaAs using nano-crystals that are capable of acceptable optical emission properties due to efficient injection of electrons and holes, modification of band structure, and modification of surface properties.
Accordingly, a first embodiment of a light emitting device is disclosed comprising a bottom layer of electrically conductive material. A block of electrically insulating material is disposed on the bottom layer. At least a portion of the block is optically transparent. A top layer of electrically conductive material is disposed on the block. A plurality of discrete nano-crystals of a material selected from the group consisting of Group IV, Group III-V, and Group II-VI is disposed within the block, and are thereby electrically insulated from the top and bottom layers. Also provided are bottom and top electrodes connected to the bottom and top layers, respectively, for applying a voltage therebetween.
A variation of the first embodiment of the light emitting device is also disclosed wherein the block comprises a bottom layer of said electrically insulating material having the nano-crystals disposed thereon and a top layer of the electrically insulating material formed over the nano-crystals.
A second embodiment of the light emitting structure of the present invention is also disclosed wherein a plurality of said blocks are stacked upon one another. The plurality of blocks being disposed between the bottom layer and the top layer.
A variation of the second embodiment of the light emitting device is also disclosed wherein each block comprises a bottom layer of said electrically insulating material having a bottom plurality of discrete nano-crystals disposed thereon, at least one middle layer of electrically insulating material formed over the bottom nano-crystals and having a middle plurality of nano-crystals disposed thereon, and a top layer of electrically insulating material formed over the last middle plurality of nano-crystals.
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Chan Kevin Kok
Tiwari Sandip
International Business Machines - Corporation
Jackson, Jr. Jerome
Scully Scott Murphy & Presser
Underweiser, Esq. Marian
Wilson Allan R.
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