[background technology]
Opto-electronics prosperity in recent years, light-emitting diode (Light Emitting Diode, LED) because have that volume is little, energy consumption is low, high brightness, the life-span is long and luminous advantage such as stable, be widely used in display unit and the light read-write equipment.
In the making of light-emitting diode, because compound semiconductor is direct gap semiconductor (Direct Semiconductor), have preferable luminous efficiency, therefore main at present still based on compound semiconductor.But obviously (Ge) cost is high for C, Si, so how industry all utilizes IV family semiconductor fabrication light-emitting diode in research than IV family semiconductor for compound semiconductor.IV family semiconductor is a non-direct gap semiconductor (IndirectSemiconductor), on luminescence theory owing to be difficult for to observe the law of conservation of momentum, therefore luminous efficiency is not high, with silicon (Si) or germanium (Ge), the light that its electron-hole recombinations (Electron-holeRecombination) is produced is that infrared ray and efficient are not good.On IV family semiconductor visible light light-emitting diode was made, (SiliconCarbon, SiC) thin-film led, it has higher energy gap, and (Energy Bandgap, Eg), its energy gap was approximately 3eV to the successful at present carborundum that blue light-emitting is arranged.
Seeing also Fig. 1, is a kind of light-emitting diode structure schematic diagram of prior art.This light-emitting diode 1 comprises that p type carborundum (p-SiC) substrate 11, is formed on n type silicon carbide layer 12, on this p type silicon carbide substrates 11 and is formed on p type Ohmic electrode 15, that n type aln layer (n-AlN) 13, on this n type silicon carbide layer 12 is formed on these p type silicon carbide substrates 11 bottoms and is formed on n type Ohmic electrode 16 on this n type aln layer 13.
Seeing also Fig. 2, is that light-emitting diode shown in Figure 1 can be with schematic diagram when not applying bias voltage.There are a plurality of holes 111 in the valence band 131 of this p type silicon carbide substrates 11, there are a plurality of electronics 122 in the conduction band 132 of this n type silicon carbide layer 12 and this n type aln layer 13, because the existence at the interface of this p type silicon carbide substrates 11 and this n type silicon carbide layer 12 can be with difference (Bandgap Offset), a plurality of holes 111 can't be to valence band 131 migrations of this n type silicon carbide layer 12 in the valence band 131 of this p type silicon carbide substrates 11, simultaneously, a plurality of electronics 122 also can't be to conduction band 132 migration of this p type silicon carbide substrates 11 in the conduction band 132 of this n type silicon carbide layer 12, and these a plurality of holes 111 and these a plurality of electronics 122 can compound (Recombination).
Seeing also Fig. 3, is that light-emitting diode shown in Figure 1 can be with schematic diagram when applying forward bias.When applying forward bias, the difference of being with that exists at the interface of this p type silicon carbide substrates 11 and this n type silicon carbide layer 12 reduces.A plurality of holes 111 are to valence band 131 migrations of this n type silicon carbide layer 12 in the valence band 131 of this p type silicon carbide substrates 11, and simultaneously, a plurality of electronics 122 are to conduction band 132 migrations of this p type silicon carbide substrates 11 in the conduction band 132 of this n type silicon carbide layer 12.Electronics 122 in the conduction band 132 of this n type silicon carbide layer 12 is compound with the hole 111 in the valence band 131 that enters this n type silicon carbide layer 12, launches photon simultaneously, and the wavelength of the corresponding light wave of light emitted son is determined by following formula:
λ=1240/Eg(nm)
λ is an optical wavelength in the formula, and Eg is the energy gap of semi-conducting material.The energy gap of this n type silicon carbide layer 12 is approximately 3.0eV, and the light emitted wave-wave of this light-emitting diode is long to be 470nm, i.e. blue light.
But carborundum is non-direct gap semiconductor (Indirect Semiconductor), so this lumination of light emitting diode efficient is not high.Simultaneously, aluminium nitride is the III-V compounds of group, and cost is higher.
[embodiment]
Seeing also Fig. 4, is the structural representation of first execution mode of light-emitting diode of the present invention.This light-emitting diode 2 comprises that a transparency carrier 21, is formed on anode electrode 22, on this transparency carrier 21 and is formed on insulating barrier 23, on this anode electrode 22 and is formed on luminescent layer 24, in this insulating barrier 23 and is formed on cathode electrode 25 on this insulating barrier 23.Wherein, this insulating barrier 23 is divided into one first insulating barrier 23a and one second insulating barrier 23b, and this luminescent layer position at this first insulating barrier 23a and this second insulating barrier 23b at the interface.This transparency carrier 21 is glass or resin.This anode electrode 22 has the corresponding anode electrode pattern according to luminous situation, this anode electrode 22 has higher work function (Work Function), for example tin indium oxide (Indium Tin Oxide, ITO) or indium zinc oxide (Indium ZincOxide, IZO) etc.The energy gap of this insulating barrier 23 is greater than the energy gap of this luminescent layer and less than 6eV, and its material is silicon nitride (Si
3N
4), fire sand (SiCN), silicon oxynitride (SiON), nitrogen siloxicon (SiCON) etc., the thickness of this insulating barrier 23 is 60nm to 150nm.This luminescent layer 24 comprises a plurality of carborundum (Si
xC
1-x, 0<x<1) and nano dot, this nanometer silicon carbide spot diameter is 5nm to 50nm.This cathode electrode 25 has corresponding cathode electrode pattern according to luminous situation, and this cathode electrode 25 has higher work function (Work Function), for example alloy of the alloy of lithium fluoride and aluminium, barium, calcium and aluminium etc.
See also Fig. 5, be light-emitting diode shown in Figure 4 can be with schematic diagram.There are a plurality of electronics 260 in the conduction band 26 of this nanometer silicon carbide point 24, have a plurality of holes 270 in its valence band 27.When this light-emitting diode 2 does not apply bias voltage, because carborundum belongs to non-direct gap semiconductor, electronics in its conduction band and the hole in the valence band are difficult for observing the law of conservation of momentum, therefore these a plurality of electronics 260 and these a plurality of holes 270 are difficult for compound, the quantity in these a plurality of electronics 260 and these a plurality of holes 270 is very little again, so both are difficult to compound.When applying forward bias, under extraneous effect of electric field, hole 270 in the valence band 27 of this anode electrode 22 is moved in the valence band 27 of this first insulating barrier 23a and is entered in the valence band 27 of this nanometer silicon carbide point 24, simultaneously, the electronics 260 in the conduction band 26 of this cathode electrode 25 moves in the conduction band 26 of this second insulating barrier 23b and enters in the conduction band 26 of this nanometer silicon carbide point 24.This first, second insulating barrier 23a, 23b and this nanometer silicon carbide point 24 can be with difference (Bandgap Offset) bigger, enter the valence band 27 of this nanometer silicon carbide point 24 and a plurality of holes 270 in the conduction band 26 and a plurality of electronics 260 and can be limited in this nanometer silicon carbide point 24.When the material yardstick became one dimension (1D) quantum wire (Quantum Wire) or zero dimension (0D) quantum dot (Quantum Dot) by two dimension (2D) quantum well (Quantum Well) micro, quantum effect just can display.By quantum confinement effect as can be known, these a plurality of holes 270 and the motion of a plurality of electronics 260 on three-dimensional all are restricted.By uncertainty principle as can be known, when the amount of variability of these a plurality of holes 270 and a plurality of electronics 260 yardsticks more hour, the not accuracy of its momentum will be big more, its probability of observing the law of conservation of momentum also can be big more, these a plurality of holes 270 and a plurality of electronics 260 compound probability also can be big more, and therefore luminous efficiency is improved.The wavelength of the corresponding light wave of light emitted son is still by following formula decision:
λ=1240/Eg(nm)
By following formula as can be known, when energy gap changes, the also corresponding change of the wavelength of light emitted ripple.Carbon, siliceous amount percentage can change the energy gap size of this nanometer silicon carbide point 24 in this nanometer silicon carbide point 24 of modulation, thereby make this light-emitting diode 2 launch the light wave of different wave length.
This luminescent layer 24 also can be made up of a plurality of silicon carbide alloys nano dots.This silicon carbide alloys nano dot is mixed by silicon nano dots and carbon nano dot, or is mixed by nanometer silicon carbide point and silicon nano dots.
When the mass percent of carbon in this nanometer silicon carbide point or this silicon carbide alloys nano dot greater than 70% the time, the light wave of these light-emitting diode 2 emissions be ultraviolet; When the mass percent of carbon in this nanometer silicon carbide point or this silicon carbide alloys nano dot greater than 15% and less than 70% the time, the light wave of these light-emitting diode 2 emissions is a visible light; When the mass percent of carbon in this nanometer silicon carbide point or this silicon carbide alloys nano dot less than 15% the time, the light wave of these light-emitting diode 2 emissions is an infrared ray.
Seeing also Fig. 6, is the structural representation of second execution mode of light-emitting diode of the present invention.The structure of this light-emitting diode 3 and light-emitting diode 2 shown in Figure 4 is roughly the same, and its difference is: the luminescent layer 34 of this light-emitting diode 3 is sandwich construction.
Seeing also Fig. 7, is the structural representation of the 3rd execution mode of light-emitting diode of the present invention.The structure of this light-emitting diode 4 and light-emitting diode 2 shown in Figure 4 is roughly the same, and its difference is: this luminescent layer 44 comprises a plurality of carbonization germanium (Ge
xC
1-x, 0<x<1) and nano dot or carbonization germanium alloy nano dot.This carbonization germanium alloy nano dot is mixed by germanium nanopoint and carbon nano dot, or is mixed by carbonization germanium nanopoint and germanium nanopoint.
When the mass percent of carbon in this carbonization germanium nanopoint or this carbonization germanium alloy nano dot greater than 72% the time, the light wave of these light-emitting diode 4 emissions be ultraviolet.When the mass percent of carbon in this carbonization germanium nanopoint or this carbonization germanium alloy nano dot greater than 23% and less than 72% the time, the light wave of these light-emitting diode 4 emissions is a visible light.When the mass percent of carbon in this carbonization germanium nanopoint or this carbonization germanium alloy nano dot less than 23% the time, the light wave of these light-emitting diode 4 emissions is an infrared ray.
Seeing also Fig. 8, is the structural representation of the 4th execution mode of light-emitting diode of the present invention.The structure of this light-emitting diode 5 and light-emitting diode 2 shown in Figure 4 is roughly the same, and its difference is: this luminescent layer 54 comprises a plurality of germanium silicide (Si
xGe
1-x, 0<x<1) and nano dot or germanium silicide alloy nano point.This germanium silicide alloy nano point is mixed by germanium silicide nano dot and silicon nano dots, or is mixed by germanium silicide nano dot and germanium nanopoint, or is mixed by silicon nano dots and germanium nanopoint.The light wave of these light-emitting diode 5 emissions is an infrared ray.During this germanium silicide nano dot or germanium silicide alloy nano point small-sized, its quantum effect is obvious, and its energy gap can become greatly, and the probability of these light-emitting diode 5 visible emitting also can increase, when the size micro arrived to a certain degree, the light wave of these light-emitting diode 5 emissions was a visible light.
Seeing also Fig. 9, is the structural representation of the 5th execution mode of light-emitting diode of the present invention.The structure of this light-emitting diode 6 and light-emitting diode 2 shown in Figure 4 is roughly the same, and its difference is: this luminescent layer 64 comprises a plurality of carbonization SiGe (Si
xGe
yC
1-x-y, 0<x<1,0<y<1) and the alloy nano point.This carborundum germanium alloy nano dot is mixed by silicon nano dots and carbonization germanium nanopoint, or mix by silicon nano dots and carborundum germanium nanopoint, or mix by germanium silicide nano dot and nanometer silicon carbide point, or mix by germanium silicide nano dot and carbonization germanium nanopoint, or mix by germanium silicide nano dot and carborundum germanium nanopoint, or mix by nanometer silicon carbide point and carbonization germanium nanopoint, or mix by nanometer silicon carbide point and carborundum germanium nanopoint, or mix by germanium nanopoint and nanometer silicon carbide point, or mix by germanium nanopoint and carborundum germanium nanopoint, or mix, or by the carbon nano dot by carbonization germanium nanopoint and carborundum germanium nanopoint, germanium nanopoint and silicon nano dots mix.
When the composition of carbon in the carborundum germanium alloy nano dot greater than 75% the time, this light-emitting diode 6 is launched light wave and is ultraviolet ray, when the mass percent of carbon in the carborundum germanium alloy nano dot greater than 32% and less than 75% the time, it is visible light that this light-emitting diode 6 is launched light wave, when the mass percent of carbon in the carborundum germanium alloy nano dot less than 32% the time, it is infrared ray that this light-emitting diode 6 is launched light wave.
The luminescent layer of light-emitting diode 2 of the present invention comprises a plurality of IV family semiconductor nano point, and its quantum effect is obvious, the luminous efficiency height.Simultaneously, this luminescent layer material cost is lower.