TWI662106B - Rare earth element light emitting diode structure with barrier layer - Google Patents

Abstract

The invention is a rare-earth element light-emitting diode structure which is promoted to operate under reverse bias by means of an interface barrier layer. A barrier layer with an energy level higher than that of the material of the light-emitting layer is mainly formed on a side interface of the rare-earth element light-emitting layer. Through the operation of different bias voltages, this barrier layer can control the situation of carriers entering the light emitting layer. Compared with the rare-earth element light-emitting diode without barrier layer, the rare-earth element light-emitting diode with barrier layer can suppress the dark current when the threshold voltage is not reached, and increase the light-emitting intensity of the diode after the threshold voltage is exceeded.

Description

Rare earth element light emitting diode structure with barrier layer

The invention relates to a structure for improving the luminosity of the light-emitting diode by using an interface barrier layer method in an electrically excited rare earth element light-emitting diode structure.

An electrically excited rare earth element light-emitting diode is a light-emitting layer containing a rare earth element-containing material in a diode structure, and uses an electrically excited downloader to transition from the energy state of these rare earth elements to emit a wavelength corresponding to the energy state of the rare earth element. A light-emitting diode. Unlike conventional diodes that operate under forward bias, this light-emitting diode structure can emit light due to the energy-state transition of the rare earth element due to the impact of electrons and or holes on the rare earth element under reverse bias.

Referring to the research [G.Franzo et al, Appl. Phys. Lett. 64 (17), pp2235-2237 (1994)], in order to implant the Er element into the PN diode structure by ion implantation, the subsequent 620 High temperature heat treatment at ℃ to achieve electrical excitation.

With reference to US Patent Publication No. US6846509, it discloses a method of depositing thorium oxide (Er ₂ O ₃ ) by sputtering at low temperature, and using subsequent heat treatment at a temperature higher than 600 ° C. to increase the intensity of its light-excitation light. .

Reference paper research [S. Iwan et al, Physica B 407, pp2721-2724 (2012)], in order to mix ytterbium acetate with zinc acetate, perform a erbium-doped zinc oxide thin film at 450 ° C, and complete the practice of erbium-doped light-emitting diode elements. This method does not need to go through the subsequent high temperature heat treatment, and can directly excite the light.

Refer to the paper research [T.H. Lin et al, Sensors and Materials, 30, pp939-946 (2018)], in order to add an ohmic contact layer on the light emitting layer. This structure can reduce the resistance of the light-emitting diode and improve the quality of the device.

For this reason, the applicant has conducted experiments and researches to propose a structure that can enhance the quality of this kind of rare-earth light-emitting diode, especially a heterostructure with a barrier layer. An obstacle layer is introduced next to the light-emitting layer, so that the characteristics of the device reach the current suppression when the operating voltage is lower than the critical voltage, and the brightness is increased when the operating voltage is higher than the critical voltage, thereby improving the efficacy of the quality of the light-emitting diode.

The reason is that the inventors have taken this into consideration, and based on many years of rich design and development and practical manufacturing experience in the relevant industry, research and improve the existing technology and defects, and provide a rare earth element light-emitting diode structure with a barrier layer in order to achieve more For the purpose of good practical value.

In view of the above-mentioned conventional technologies, the main object of the present invention is to propose a structure capable of improving the quality of a rare-earth light-emitting diode. A barrier layer (highly conductive band-level material) is introduced next to the light-emitting layer, so that the characteristics of the device reach the operating voltage. The current suppression below the critical voltage and the increase in light brightness above the critical voltage improve the efficacy of the quality of such light-emitting diodes.

In order to achieve the above object, the present invention proposes a structure capable of improving the quality of a rare earth element light emitting diode including: a substrate metal contact layer; a p-type material formed on the substrate metal contact layer; a doped rare earth element light emitting layer Is formed on the p-type material; an n-type material is formed on the doped rare earth element light-emitting layer; and an upper metal contact layer is formed on the n-type material; wherein the p-type material is near The material end of the doped rare earth element light emitting layer forms a highly conductive band-level material to be combined with the doped rare earth element light emitting layer; or the n-type material is formed near the material end of the doped rare earth element light emitting layer to form the The highly conductive band-level material is combined with the doped rare earth element light-emitting layer; or the p-type material and the n-type material are formed near the material end of the doped rare-earth element light-emitting layer to form the highly conductive band-level material with The doped rare earth element light emitting layer is combined.

Preferably, the p-type material and the n-type material are selected from a semiconductor material, a polymer material, or a combination thereof.

Preferably, the p-type material and the n-type material are selected from zinc oxide, magnesium oxide, silicon dioxide, rare earth elements, or a combination thereof.

Preferably, the substrate metal contact layer and the upper metal contact layer may be selected from indium, gold, nickel, nickel oxide, indium tin oxide, or a combination thereof.

Preferably, the p-type material, the n-type material and the doping method are selected from spray coating, thermal evaporation, electron beam evaporation, sputtering, vapor deposition, liquid deposition, or a combination thereof.

In the invention, a material is prepared beside a rare earth element-containing light emitting layer in a light emitting diode structure with a rare earth element, and the energy level of this material is higher than that of the light emitting layer: p-type doped end to make a barrier layer material with high conductivity; n-type doped end to make a barrier layer material with high conductivity; or a combination of both to improve the quality of this type of light emitting diode .

The above summary and the following detailed description and drawings are to further explain the methods, means and effects adopted by this creation to achieve the intended purpose. The other purposes and advantages of this creation will be explained in the subsequent description and drawings.

101‧‧‧ Substrate metal contact layer

201‧‧‧p-type material

301‧‧‧luminescent layer

401‧‧‧n type material

501‧‧‧ over metal contact layer

202, 402‧‧‧ Highly Conductive Band Energy Level Materials

(a) ‧‧‧ Before improvement

(b) ‧‧‧ After improvement

V‧‧‧ reverse bias

I‧‧‧ current

L‧‧‧ Brightness

λ‧‧‧wavelength

Figure 1 is a schematic diagram of the structure of a light-emitting diode with a rare earth element; Figure 2 is a schematic diagram of a modified structure of a light-emitting diode with a rare earth element; Figure 3 is a schematic diagram of a conductive energy band; and Figure 4 is a diagram before improvement ( a), without the silicon dioxide layer, and after improvement (b), the relationship between the reverse bias voltage V and the current I of the erbium-doped zinc-magnesium oxide light-emitting diode with the silicon dioxide layer; a), without the silicon dioxide layer, and after improvement (b), the relationship between the brightness L and the current I of the erbium-doped zinc-magnesium oxide light-emitting diode with the silicon dioxide layer; Figure 6 shows the before improvement (a) , Without silicon dioxide layer, and after improvement (b), erbium-doped zinc-magnesium oxide light-emitting diodes with silicon dioxide layer Spectrogram; Figure 7 is a schematic diagram of the structure of an improved rare earth element light emitting diode above the light emitting layer; Figure 8 is a schematic diagram of the structure of an improved rare earth element light emitting diode above the light emitting layer.

The following is a description of specific embodiments of the present invention. Those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification.

Please refer to Figure 1, which is a schematic diagram of the traditional structure of a light emitting diode with a rare earth element. As shown in the figure, the structure includes a substrate metal contact layer 101 and a p-type material 201, and then a process such as evaporation, sputtering, chemical vapor phase, spraying, immersion, etc. is performed on the p-type material 201, or The combination method completes a light-emitting layer 301 containing a rare earth element, an n-type material 401, and an upper metal contact layer 501. The p-type material 201 and the n-type material 401 can be selected from semiconductor materials, polymer materials, or a combination of the above, for example Zinc oxide, magnesium oxide, silicon dioxide, rare earth elements, or a combination thereof. The substrate metal contact layer 101 and the upper metal contact layer 501 may be selected from indium, gold, nickel, nickel oxide, indium tin oxide, or a combination thereof. In this embodiment, the substrate metal contact layer 101 is indium metal, and the p-type material 201 is a p-type silicon substrate having a concentration of 1 × 10 ¹⁹ cm ⁻³ . The light-emitting layer 301 is erbium-doped zinc-magnesium oxide (Mg _0.04 Zn _0.96 O: Er) with a thickness of 400 nm and a concentration of 3x10 ¹⁷ cm ^-3 , and the n-type material 401 is an n-type indium doped with a thickness of 200 nm and a concentration of 1x10 ¹⁸ cm ^-3 Zinc oxide (ZnO: In). The upper metal contact layer 501 is made of gold (Au) metal with a thickness of 300 nm by a sputtering method. The light-emitting layer 301 and the n-type material 401 are manufactured by using magnesium acetate, zinc acetate, and an aqueous solution of osmium acetate as precursors, and sequentially by spray pyrolysis at 450 ° C.

In the structure of FIG. 1, during the reverse bias operation, electrons are generated in the region 201 of the p-type material, while holes are generated in the region 401 of the n-type material, and enter the erbium-doped zinc oxide magnesium light-emitting layer 301 under the reverse bias. . Since the carrier continues to enter this region with the increase of the reverse bias voltage, a continuous current enters before the reverse bias voltage reaches the threshold voltage that produces the impact free emission. These currents do not cause light to strike the dissociation mechanism, which is an ineffective current for the light-emitting mechanism. In addition to the large reactive current that requires a higher power supply to drive the component, the heat it generates also indirectly affects the characteristics of the component.

In order to improve the above disadvantages, to suppress the current before the reverse bias voltage reaches the critical voltage, and to form a high electric field and smoothly introduce the current after the critical voltage is exceeded, we introduce a high-level material into the structure. Please refer to Figure 2 for a schematic diagram of the improved structure of a light emitting diode with a rare earth element. The high-conductivity-band energy-level material 202 is a high-energy-level material, and the remaining structures and methods are the same as those in FIG. 1. In an embodiment, the high-conductivity band-level material 202 is silicon dioxide (SiO ₂ ). The manufacturing method is that the p-type material 201 is placed in a high-temperature furnace containing water gas, and the silicon dioxide is formed at a temperature of 450 ° C. or higher for 10 minutes to be combined with the doped rare earth element light-emitting layer 301.

FIG. 3 is a schematic diagram of the improved conductive energy band, including the conductive band of the p-type material 201, the high conductive band energy step material 202, and the erbium-doped zinc magnesium oxide light-emitting layer 301. Before the improvement (a) in the figure, the conductive energy band diagram with the applied bias voltage lower than the critical voltage is shown, and after the improvement (b) is the conductive energy band diagram with the applied bias voltage higher than the critical voltage. When the bias voltage is not applied or the applied bias voltage does not reach the threshold voltage value, the electrons generated by the p-type material 201 layer are blocked by the high-conductivity band-level material 202 of the barrier layer and cannot enter the light-emitting layer 301 layer. In this way, the current at this time is suppressed. When the applied bias voltage is higher than the threshold voltage, it can be seen from the improved figure (b) in FIG. 3 that the energy band bending in the region 202 of the high-conductivity band energy-level material is large. At this time, electrons can use the Fowler-Nordheim tunneling method. Entering the light-emitting layer 301, the impact ionization effect generated by the high electric field at this time is better, thereby improving the brightness of the element.

Figure 4 shows the relationship between the reverse bias voltage V and the current I of the erbium-doped zinc-magnesium oxide light-emitting diode with a silicon dioxide layer before the improvement (a) and without the silicon dioxide layer (b). From this figure, it can be seen that under the same bias, the device with a silicon dioxide barrier layer has a lower device current value as shown in (b) after the improvement.

Figure 5 shows the relationship between the brightness L and the current I of the erbium-doped zinc-magnesium oxide light-emitting diode with a silicon dioxide layer (b) before the improvement and (b) the silicon dioxide layer after the improvement. From this figure, we can see that before the improvement (a), the zinc-magnesium oxide light-emitting diode needs a current of 20 mA to have a significant light output. The improved light-emitting diode (b) has a significant light output at a current of 10 mA. At the same current, a device with a silicon dioxide barrier layer has a higher brightness.

Fig. 6 is a spectrum diagram of the erbium-doped zinc-magnesium oxide light-emitting diode with a silicon dioxide layer before the improvement (a) and without the silicon dioxide layer (b) after the improvement at 60 mA. Wherein the observed wavelength λ 537nm 558nm green and 660nm to generate red, corresponding to the carrier in Er ^{3+ _{4 S 3/2 → 4 I 15/2,}} 4 H 11/2 → 4 I 15 / ₂ and ⁴ F _9/2 → ⁴ I _15/2 energy step transitions. Before and after the improvement, the spectral distribution of each band is the same, and only the intensity of the brightness L is different.

The above-mentioned embodiments are merely illustrative for describing the features and effects of the present invention, and are not intended to limit the scope of the essential technical content of the present invention. According to the spirit of the present invention, a high-energy-level material can also be applied on the light-emitting layer 301 as shown in FIG. 7. The high conductive band energy step material 402 is a high energy step material that prevents holes from entering the light emitting layer 301, and has a similar effect to that shown in FIG. 2. Or, as shown in FIG. 8, the p-type material 201 and the n-type material 401 are formed near the material end of the doped rare-earth element light-emitting layer 301 with highly conductive band-level materials 202 and 402 to be combined with the doped rare-earth element light-emitting layer 301 . Anyone skilled in the art can modify and change the above embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention should be listed in the scope of patent application described later.

The p-type material 201, the n-type material 401 and the doping method of the present invention can be selected from spray coating, thermal evaporation, electron beam evaporation, sputtering, vapor deposition, liquid deposition, or a combination thereof.

In summary, the present invention utilizes the introduction of a barrier layer (highly conductive band-level materials 202, 402) beside the light-emitting layer 301, so that the device characteristics reach the current suppression when the operating voltage is lower than the critical voltage, and when the operating voltage is higher than the critical voltage. Brightness Enhance, enhance the efficacy of the quality of this light-emitting diode.

The above-mentioned embodiments are merely illustrative for describing the features and effects of the present invention, and are not intended to limit the scope of the essential technical content of the present invention. Anyone skilled in the art can modify and change the above embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention should be listed in the scope of patent application described later.

Claims (5)

A rare earth element light-emitting diode structure with a barrier layer includes: a substrate metal contact layer; a p-type material formed on the substrate metal contact layer; a light emitting layer doped with a rare earth element; On the p-type material; an n-type material is formed on the doped rare earth element light-emitting layer; and an upper metal contact layer is formed on the n-type material; wherein the p-type material is near the doped rare earth The material end of the element light-emitting layer forms a highly conductive band-level material to be combined with the doped rare-earth element light-emitting layer; or the n-type material forms the high-conduction band energy near the material end of the doped rare-earth element light-emitting layer. Materials are combined with the doped rare-earth element light-emitting layer; or the p-type material and the n-type material form the high-conductivity band-energy-level material at the material end near the doped rare-earth element light-emitting layer to interact with the doped rare-earth element. The element light emitting layer is combined, wherein the high-conductivity band-level material is silicon dioxide. The light-emitting diode structure according to item 1 of the scope of the patent application, wherein the p-type material and the n-type material are selected from a semiconductor material, a polymer material, or a combination thereof. The light-emitting diode structure according to item 1 of the scope of the patent application, wherein the p-type material and the n-type material are selected from the group consisting of zinc oxide, magnesium oxide, silicon dioxide, rare earth elements, or a combination thereof. The light-emitting diode structure according to item 1 of the scope of the patent application, wherein the substrate metal contact layer and the upper metal contact layer are selected from indium, gold, nickel, nickel oxide, indium tin oxide, or a combination thereof. The light-emitting diode structure according to item 1 of the scope of patent application, wherein the p-type material, the n-type material, and the doping method are selected from the group consisting of spray coating, thermal evaporation, electron beam evaporation, sputtering, Vapor deposition, liquid deposition or a combination thereof.