KR20060121450A - Light emitting device equipped with dielectric layer - Google Patents

Abstract

A light emitting device having a dielectric layer is provided to perform operational functions with AC power without using an additional device by including a capacitor function layer. An n-compound semiconductor layer(110) having an etched part is formed on a substrate(100). An active layer(120) is formed on an unetched part of the n-compound semiconductor layer. A first p-compound semiconductor layer(130) is formed on the active layer. A dielectric layer(140) is formed on the first p-compound semiconductor layer. A second p-compound semiconductor layer(150) is formed on the dielectric layer. A p-electrode(180p) is formed on the second p-compound semiconductor layer. An n-electrode(180n) is formed on the etched part of the n-compound semiconductor layer.

Description

Light emitting device equipped with dielectric layer

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of a first embodiment of a light emitting device having a dielectric layer of the present invention.

Fig. 2 is a sectional view of a second embodiment of a light emitting element with a dielectric layer of the present invention.

3 is a circuit diagram of a light emitting device having a dielectric layer of the present invention.

* Description of symbols on the main parts of the drawings *

100, 200: substrate. 110, 210: n-compound semiconductor layer.

120, 220: active layer. 140, 250: dielectric layer.

170, 270: protective layer. 180p, 280p: p-electrode.

180n, 280n: n-electrode. 130: First p-compound semiconductor layer.

150: second p-compound semiconductor layer. 160: conductor layer.

230: p-compound semiconductor layer. 240: First conductor layer.

260: Second conductor layer.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device having a dielectric layer, and in particular, to form a light emitting device on an upper surface of the substrate, including a dielectric layer functioning as a capacitor for charging charge, thereby eliminating the use of another separate device. The present invention relates to a light emitting device having a dielectric layer which is convenient because the light emitting device can operate when an AC power is applied, and does not cause an increase in volume and an increase in price for driving the light emitting device to an AC power source.

A light emitting device basically consists of a junction between a p-type and an n-type semiconductor, and is a type of optoelectronic device that emits energy corresponding to a bandgap of a semiconductor in the form of light by applying electrons and holes when voltage is applied. )to be. The amount of light output from the light emitting device increases in proportion to the current flowing through the diode. Light emitting devices are environmentally friendly and have high energy saving effects along with advantages such as high processing speed and low power consumption of semiconductors, and thus they are used in many fields such as large display boards, traffic lights, and automotive instrument panels.

In general, a light emitting device has a multilayer semiconductor layer in which n contact layers, active layers, and p contact layers are sequentially stacked on a substrate, and has n type electrodes and p type electrodes formed on the n contact layers and p contact layers. . In operation of the light emitting device, when a forward voltage is applied between the two electrodes, electrons are injected from the n-type electrode through the n-contact layer and holes are injected into the active layer from the p-type electrode through the p-contact layer. In this case, electrons and holes injected into the active layer recombine with each other to emit light corresponding to a band gap or energy level difference of the active layer.

The voltage applied between the two electrodes is a voltage generated from a direct current power source, and a light emitting device emits light by applying a positive electrode to a p-type electrode and a negative electrode to an n-type electrode. Therefore, the light emitting device can be used in many fields such as a headlight of a mobile phone or a car.

However, when an AC power source is to be used, such as a luminaire, the light emitting device emits light during a time when a forward voltage is applied to two electrodes of the light emitting device. However, there was a possibility that the light emitting device could burn when a reverse voltage exceeding the withstand voltage characteristic of the light emitting device was applied. Therefore, when AC power is used for the light emitting device, a voltage is applied to the light emitting device in a forward direction by using a converter that converts the AC power into DC. In addition, the chip inductor or the chip capacitor is connected to the outside of the light emitting device so that the light emitting device does not burn even when the reverse voltage is applied to the light emitting device.

In the case of using the conventional methods described above, in order to drive the light emitting device using an AC power source, a separate device must be used to be electrically connected to the light emitting device, so that the volume increases and the cost increases. There was this.

Therefore, an object of the present invention is to form a light emitting device on a substrate, including a layer that functions as a capacitor, so that the light emitting device can operate when AC power is applied without using any other device. The present invention relates to a light emitting device having a dielectric layer which does not increase in volume and increase in price for operating the light emitting device as an AC power source.

The light emitting device having the dielectric layer of the present invention having the above object includes an n-compound semiconductor layer formed on an upper surface of a substrate and etched a part of the upper portion thereof, an active layer formed on an unetched upper surface of the n-compound semiconductor layer, A first p-compound semiconductor layer formed on an upper surface of the active layer, a dielectric layer formed on an upper surface of the first p-compound semiconductor layer, a second p-compound semiconductor layer formed on an upper surface of the dielectric layer, and the second p-compound And a p-electrode formed on the upper surface of the semiconductor layer, and an n-electrode formed on the etched upper surface of the n-compound semiconductor layer.

And a conductor layer formed on the upper surface of the second p-compound semiconductor layer.

A protective layer is formed on the entire upper portion of the substrate except for the upper portion of the conductor layer and the upper portion of the etched portion of the n-compound semiconductor layer.

The conductor layer is characterized by consisting of indium tin oxide.

In addition, the light emitting device having the dielectric layer of the present invention includes an n-compound semiconductor layer formed on the upper surface of the substrate and etched a part of the upper portion, an active layer formed on the unetched upper surface of the n-compound semiconductor layer, and the active layer. A p-compound semiconductor layer formed on the upper surface, a first conductor layer formed on the upper surface of the p-compound semiconductor layer, a dielectric layer formed on the upper surface of the first conductor layer, a second conductor layer formed on the upper surface of the dielectric layer, And a p-electrode formed on the upper surface of the second conductor layer and an n-electrode formed on the etched upper surface of the n-compound semiconductor layer.

A protective layer is formed on the entire upper portion of the substrate except for a portion of the upper surface of the second conductor layer and a portion of the upper surface of the etched portion of the n-type compound semiconductor layer.

The dielectric is characterized in that the aluminum nitride (AlN) or zinc oxide (ZnO).

Hereinafter, a light emitting device having a dielectric layer according to the present invention will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a first embodiment of a light emitting device having a dielectric layer of the present invention. As shown, the n-compound semiconductor layer 110 formed on the upper surface of the substrate 100 and partially etched thereon, and the active layer 120 formed on the unetched upper surface of the n-compound semiconductor layer 110; A first p-compound semiconductor layer 130 formed on an upper surface of the active layer 120 and doped with a p-type carrier, and a dielectric formed on an upper surface of the first p-compound semiconductor layer 130. A dielectric layer 140, a second p-compound semiconductor layer 150 formed on the top surface of the dielectric layer 140 and doped with a p-type carrier, and a top surface of the second p-compound semiconductor layer 150. A protective layer formed on the entire upper surface of the substrate 100 except for a conductive layer 160 made of a conductive material, a portion of the upper surface of the conductive layer 160, and a portion of the upper surface of the n-compound semiconductor layer 110. The layer 170 and the protective layer 170 are not formed on the upper surface of the conductor layer 160. Consists of the p- electrode (180p) and, n- electrode (180n) formed on the upper face is not formed, a protective layer 170 at portions of the n- semiconductor compound layer 110.

The n-compound semiconductor layer 110 includes five outermost electrons in a silicon (Si) semiconductor device, that is, nitrogen (N), phosphorus (P), and arsenic (As), which are elements of Group 5 on the periodic table of elements. ) Is a semiconductor layer doped. The n-compound semiconductor layer 110 emits electrons when a negative voltage is applied. A portion of the upper portion of the n-compound semiconductor layer 110 is etched.

The active layer 120 is formed on an unetched upper surface of the n-compound semiconductor layer 110. When the holes and the electrons are injected, the active layer 120 emits light corresponding to the band gap or the energy level difference of the active layer 120 while the electrons and the holes are recombined with each other.

The first p-compound semiconductor layer 130 includes three outermost electrons in the silicon semiconductor device, that is, boron (B), aluminum (Al), and indium (In), which are elements of Group 3 on the periodic table of elements. , Gallium (Ga) or the like is doped semiconductor layer. The first p-compound semiconductor layer 130 emits holes when a positive voltage is applied and is formed on the top surface of the active layer 120.

The dielectric layer 140 is formed of a dielectric formed on the top surface of the first p-compound semiconductor layer 130 and arranged in a direction to cancel the electric field when an electric field is applied. The dielectric is, for example, a material such as aluminum nitride (AlN) or zinc oxide (ZnO). The molecules constituting the dielectric remain randomly arranged irrespective of polarity, and when the electric field is applied, the negative polarity of the molecule is attracted to the (+) side of the electric field, and toward the (-) side of the electric field. The positive polarity of the molecule is attracted.

The second p-compound semiconductor layer 150 is formed on the top surface of the dielectric layer 140. Like the first p-compound semiconductor layer 130, the second p-compound semiconductor layer 150 is doped with elements of Group 3 in the silicon semiconductor device.

The first p-compound semiconductor layer 130, the dielectric layer 140, and the second p-compound semiconductor layer 150 are combined to form a capacitor capable of charging a charge. Since the first p-compound semiconductor layer 130 forms a lower substrate of the capacitor, the second p-compound semiconductor layer forms an upper substrate of the capacitor, and a dielectric layer 140 composed of a dielectric is present between the substrates. A condenser is formed.

In addition, the n-compound semiconductor layer 110, the active layer 120, the first p-compound semiconductor layer 130, the dielectric layer 140, the second p-compound semiconductor deposited in order on the upper surface of the substrate 100 The layer 150 is deposited using a chemical vapor deposition (CVD) method, in which a gaseous compound is reacted on a heated substrate surface and a product is deposited on the substrate surface.

The conductor layer 160 is formed on the upper surface of the second p-compound semiconductor layer 150 and is made of a conductive material. The conductor layer 160 uses a transparent electrode such as indium tin oxide (ITO) or a metal having high reflectivity.

In forming the light emitting device, a metal is deposited on the upper surface of the p-compound semiconductor layer 150, and a positive power of the power for driving the light emitting device is connected to the metal. In this case, when the metal is deposited on the entire upper surface of the p-compound semiconductor layer 150, the light emitted by the light emitting device in the upper direction of the light emitting device is blocked by the metal, so that the light emitted by the light emitting device is In terms of its effectiveness. Metal is deposited only on a portion of the upper surface of the p-compound semiconductor layer in order to reduce the effect of the light on the efficient side. However, in the case of depositing only a portion of the metal, a current flows in a specific portion of the active layer.

In order to overcome the above disadvantages, the upper surface of the p-compound semiconductor layer 150 is formed of a conductive layer 160 using a material such as indium tin oxide, which is conductive and easily transmits light, and the upper surface of the conductive layer 160. Deposit metal on some of them.

In addition, the conductor layer 160 may be formed of a metal having high reflectivity on the upper surface of the p-compound semiconductor layer 150. Forming the conductor layer 160 with a highly reflective metal increases efficiency in terms of the speed of holes emitted from the p-compound semiconductor layer 160. When the light emitting device is deposited on the substrate 100 by flip chip bonding, the light emitted by the light emitting device is reflected by the highly reflective metal and is emitted in the direction of the substrate. Increases.

The protective layer 170 is formed on the entire upper surface of the substrate 100 except for a portion of the upper surface of the conductor layer 160 and a portion of the etched upper surface of the n-compound semiconductor layer 110. The protective layer 170 is to protect the light emitting device from external contamination by using an insulator or the like. That is, the light emitting device has a laminated structure, and each layer has a constant function of emitting holes or electrons when a voltage is applied, and its action may be affected by a fine material such as dust existing outside. Therefore, in order to protect the light emitting device from contaminants such as dust, the protective layer 170 is formed on the entire exposed surface of the substrate 100. However, the portion requiring electrical connection to the outside, that is, the portion to which the voltage for driving the light emitting device is applied excludes the formation of the protective layer 170.

The p-electrode 180p is formed at a portion where the protective layer 170 is not formed on the upper surface of the p-compound semiconductor layer 150. The n-electrode 180n is formed on a portion where the protective layer 170 is not formed on the etched upper surface of the n-compound semiconductor layer 110. The p-electrode 180p and the n-electrode 180n electrically connect an external power source for driving the light emitting device to the light emitting device.

2 is a cross-sectional view of a second embodiment of a light emitting device having a dielectric layer of the present invention. As illustrated, an n-compound semiconductor layer 210 having a portion of an upper portion etched is deposited on the upper surface of the substrate 200. An active layer 220, a p-compound semiconductor layer 230, a first conductor layer 240, a dielectric layer 250, and a second conductor layer 260 are formed on an unetched top surface of the n-compound semiconductor layer 210. It is formed in order. The protective layer 270 is formed on the entire exposed surface of the substrate 200 except for a part of the top surface of the second conductor layer 260 and a part of the etched top surface of the n-compound semiconductor layer 210. Is formed. The p-electrode 280p is formed on a portion where the protective layer 270 is not formed on the upper surface of the second conductor layer 260, and the protective layer 170 on the etched upper surface of the n-compound semiconductor layer 210. N-electrode 280n is formed at the portion where () is not formed.

The n-compound semiconductor layer 210, the active layer 220, and the p-compound semiconductor layer 230 are formed on the upper surface of the substrate 200 in order using chemical vapor deposition.

The first conductor layer 240 is formed on the top surface of the p-compound semiconductor layer 230. This is because in the first embodiment, since the first p-compound semiconductor layer serving as the lower substrate of the capacitor has a high resistance value, the first conductor layer 240 made of a conductive material having a low resistance value has the lower substrate 200 of the capacitor. In this case, the power generated by the light emitting device is reduced when a power source for driving the light emitting device is applied from the outside.

The dielectric layer 250 is formed on the upper surface of the first conductor layer 240, and consists of a dielectric arranged in a direction to cancel the electric field when an electric field is applied.

The second conductor layer 260 is formed on the top surface of the dielectric layer 250 and is made of a conductive material. The second conductor layer 260 increases the efficiency of the light emitted by the light emitting device and prevents the current from being driven in the active layer 220.

The first conductor layer 240, the dielectric layer 250, and the second conductor layer 260 form one capacitor. The first conductor layer 240 serves as a lower substrate of the capacitor and the second conductor layer. Reference numeral 260 serves as an upper substrate of the capacitor, and the dielectric layer 250 serves as a dielectric between both substrates of the capacitor.

The protective layer 270 is formed on the entire upper surface of the substrate 200 except for a portion of the upper surface of the second conductor layer 260 and a portion of the upper surface of the n-compound semiconductor layer 210. The protective layer 270 is made of an insulating material or the like to protect the light emitting device from external contamination.

The p-electrode 280p is formed at a portion where the protective layer 270 is not formed on the upper surface of the second conductor layer 260, and the n-electrode 280n is formed of the n-compound semiconductor layer 210. The protective layer 270 is formed on a portion where the protective layer 270 is not formed. The p-electrode 280p and the n-electrode 280n electrically connect an external power source for driving the light emitting device to the light emitting device.

3 is a circuit diagram of a light emitting device having a dielectric layer of the present invention. As shown, a capacitor C and a light emitting device D are connected in series between both nodes. That is, in the light emitting device having the dielectric layer, since the dielectric layer capable of charging the charge is formed on the upper surface of the p-compound semiconductor layer, a circuit diagram in which the light emitting device and the capacitor are connected in series is realized.

An operation of emitting light by the light emitting device by the AC power will be described. For example, a node connected to the cathode of the light emitting device is referred to as B, and an opposite node is referred to as A, and AC power is applied to both nodes. When a positive voltage (+ voltage) is applied to the node A, the capacitor C is charged, and a voltage higher than the voltage at which the light emitting device D starts to operate (hereinafter referred to as a driving voltage) is the positive electrode of the light emitting device. When applied to the positive (+) the light emitting device (D) is driven to emit light. On the contrary, when a positive voltage (+ voltage) is applied to the node B, the capacitor C discharges the charged voltage, and the light emitting device D emits light until the voltage applied to the anode is greater than or equal to the driving voltage. That is, after the capacitor C starts to discharge, the light emitting device D emits light until the voltage applied to the anode of the light emitting device D becomes less than or equal to the driving voltage. Since the power source is an AC power source, the above process is repeated according to the frequency of the power source, and thus the light emitting device D periodically emits light.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and changes of the present invention without departing from the spirit or field of the invention provided by the claims below It can be easily understood by those skilled in the art.

As described above, the present invention is convenient because it is not necessary to electrically connect another separate device to the light emitting device in order to operate the light emitting device with an AC power source, and the volume increase and price increase for operating the light emitting device with the AC power supply do not occur. .

Claims (7)

An n-compound semiconductor layer formed on an upper surface of the substrate and etched a part of the upper portion thereof; An active layer formed on an unetched upper surface of the n-compound semiconductor layer; A first p-compound semiconductor layer formed on an upper surface of the active layer; A dielectric layer formed on an upper surface of the first p-compound semiconductor layer; A second p-compound semiconductor layer formed on an upper surface of the dielectric layer; A p-electrode formed on an upper surface of the second p-compound semiconductor layer; And And a dielectric layer comprising an n-electrode formed on an etched top surface of the n-compound semiconductor layer. The method of claim 1, Further comprising a conductor layer on the upper surface of the second p- compound semiconductor layer, And the p-electrode is formed on the upper surface of the conductor layer. The method of claim 2, A protective layer is formed on the entire upper surface of the substrate except for a portion of the upper surface of the conductor layer and a portion of the upper surface of the n-compound semiconductor layer. The p-electrode is formed at a portion where the protective layer is not formed on the upper surface of the conductor layer, And the n-electrode is formed on a portion where the protective layer is not formed on the etched top surface of the n-compound semiconductor layer. The method according to any one of claims 1 to 3, The conductive layer is a light emitting device having a dielectric layer, characterized in that consisting of indium tin oxide (ITO). An n-compound semiconductor layer formed on an upper surface of the substrate and partially etched thereon; An active layer formed on an unetched upper surface of the n-compound semiconductor layer; A p-compound semiconductor layer formed on the upper surface of the active layer; A first conductor layer formed on the upper surface of the p-compound semiconductor layer; A dielectric layer formed on an upper surface of the first conductor layer; A second conductor layer formed on the top surface of the dielectric layer; A p-electrode formed on the upper surface of the second conductor layer; And And a dielectric layer comprising an n-electrode formed on an etched top surface of the n-compound semiconductor layer. The method of claim 5, A protective layer is formed on the entire upper surface of the substrate except for a portion of the upper surface of the second conductor layer and a portion of the upper surface of the n-type compound semiconductor layer. The p-electrode is formed at a portion where the protective layer is not formed on the upper surface of the second conductor layer, The n-electrode is a light emitting device having a dielectric layer, characterized in that formed on the portion where the protective layer is not formed on the etched top surface of the n- type compound semiconductor layer. The method according to any one of claims 1 to 3 and 5 to 6, And the dielectric material is aluminum nitride (AlN) or zinc oxide (ZnO).

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