LED chip with adjustable output voltage

Abstract

The invention discloses an LED chip with adjustable output voltage. The LED chip comprises a P-GaN resistance scheme and an N-GaN resistance scheme. In the P-GaN scheme, an N electrode is arranged on a right side P-type GaN layer, a bridging electrode is connected with the right side P-type GaN layer and an N-type GaN layer, and series resistance is provided by the right side P-type GaN layer; in the N-GaN scheme, an N electrode is arranged on an etched N-type GaN layer, a bridging electrode is only connected with the N-type GaN layer, and series resistance is provided by the N-type GaN layer. According to the two schemes, the width distance between the bridging electrode and the N electrode is adjusted, so that the series resistance is adjustable, and the output voltage is flexibly controlled. By adopting the photoetching process, the etching process and the metal deposition process, the method is mature and reliable in process, is suitable for different scenes, has the advantages of adjustable output voltage, definite current path, uniform current distribution and the like, and has remarkable practical value and popularization prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lighting, and more particularly to an LED chip which adjusts output voltage by connecting a GaN resistor in series inside the LED chip. Background Art

[0002] LEDs (light-emitting diodes) are usually composed of a P-GaN layer, a multi-quantum well (MQW) active region, and an N-GaN layer. The forward conduction voltage of conventional LED chips is generally in the range of 1.8–3.6V. To obtain a higher voltage or a specific voltage (such as 4V, 5V, 7V, etc.), it is usually necessary to connect multiple LED chips in series to achieve a high-voltage output of multiples of 3V. However, this series connection method is difficult to flexibly obtain non-multiple voltages, and has great limitations in practical applications.

[0003] In this process, increasing the number of series and parallel connections not only significantly increases the complexity of the external circuit, but may also cause overheating problems under high power, thereby affecting the stability and reliability of the LED chip. In addition, although external circuits (such as Buck / Boost power conversion solutions) can achieve certain voltage regulation, they are often accompanied by energy loss and increased costs.

[0004] Therefore, there is an urgent need to achieve more flexible voltage regulation inside the LED chip to alleviate the pressure of external power management, reduce system complexity, and meet a variety of non-standard voltage requirements. Summary of the invention

[0005] The present invention aims to overcome the deficiency of existing LED chips that they cannot flexibly adjust the output voltage internally. By introducing an adjustable GaN resistor into the LED chip, the output voltage can be fine-tuned. While maintaining the luminous efficiency of the LED body, it can meet the differentiated voltage requirements of different terminal applications and reduce dependence on external buck-boost circuits.

[0006] The technical solution of the present invention:

[0007] An LED chip with adjustable output voltage, comprising:

[0008] substrate;

[0009] An N-type GaN layer, a multi-quantum well (MQW) layer and a P-type GaN layer are disposed on the substrate;

[0010] A P electrode disposed on the P-type GaN layer;

[0011] N electrode, its position is set according to different structures:

[0012] In one structure, the N electrode is disposed on a right P-type GaN layer electrically isolated from a left P-type GaN layer;

[0013] In another structure, the N-electrode is disposed on the N-type GaN layer after etching away the P-type GaN layer and the multi-quantum well (MQW) layer;

[0014] The connection method of the bridge electrode is set according to different structures:

[0015] In one structure, the bridge electrode is electrically connected to the right P-type GaN layer and the N-type GaN layer;

[0016] In another structure, the bridge electrode is electrically connected to the N-type GaN layer;

[0017] There is an adjustable width interval between the bridge electrode and the N electrode to form an adjustable series resistor, and the series resistor adjusts the output voltage of the LED chip by adjusting the width interval;

[0018] The current path passes through:

[0019] In the structure where the N electrode is disposed on the right P-type GaN layer, the current path is: P electrode→left P-type GaN layer→multi-quantum well (MQW) layer→N-type GaN layer→right P-type GaN layer→N electrode;

[0020] In the structure where the N-electrode is disposed on the etched N-type GaN layer, the current path is: P-electrode→left P-type GaN layer→multi-quantum well (MQW) layer→N-type GaN layer→N-electrode.

[0021] The bridging electrode is electrically connected to the right P-type GaN layer and the N-type GaN layer, the N-electrode is arranged on the right P-type GaN layer electrically isolated from the left P-type GaN layer, the series resistor is formed by the right P-type GaN layer, and the current path is forced to pass through the multiple quantum well (MQW) layer.

[0022] A current spreading layer is provided between the left P-type GaN layer and the P electrode to improve current distribution and reduce local current density.

[0023] The bridge electrode is electrically connected to the N-type GaN layer, the N-electrode is arranged on the N-type GaN layer after the P-type GaN layer and the multi-quantum well layer are etched away, and the series resistor is formed by the N-type GaN layer.

[0024] The N-electrode is in direct contact with the N-type GaN layer without a current spreading layer.

[0025] The adjustable width spacing is achieved through a photolithography process and a metal deposition process.

[0026] The resistance value of the series resistor is proportional to the adjustable width interval.

[0027] The bridge electrode is made of a metal material, and the metal material includes gold (Au), platinum (Pt) or titanium (Ti).

[0028] The adjustable width interval has an adjustment range of 1 μm to 100 μm.

[0029] The output voltage adjustable LED chip of the present invention provides two technical solutions: in the P-GaN resistance solution, the N electrode is arranged on the right P-type GaN layer, the bridging electrode connects the right P-type GaN layer and the N-type GaN layer, the current path is P electrode→left P-type GaN layer→quantum well layer (MQW)→N-type GaN layer→right P-type GaN layer→N electrode, and the series resistance is provided by the right P-type GaN layer; in the N-GaN resistance solution, the N electrode is arranged on the etched N-type GaN layer, the bridging electrode only connects the N-type GaN layer, the current path is P electrode→left P-type GaN layer→quantum well layer (MQW)→N-type GaN layer→N electrode, and the series resistance is provided by the N-type GaN layer. Both solutions realize flexible adjustment of the output voltage through an adjustable series resistance, ensure that the current path is forced to pass through the quantum well layer, and set a current expansion layer between the P-type GaN layer and the P electrode to ensure uniform current distribution, reduce hot spot effects, and improve the luminous efficiency and stability of the LED chip.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] Adjustable output voltage: By adjusting the width spacing between the bridge electrode and the N electrode, the output voltage of the LED chip can be controlled, and non-multiple voltage output can be achieved within a single LED chip structure, avoiding a large number of series and parallel connections or external circuit modifications. It not only simplifies system design, but also provides higher flexibility. The external power management unit does not need to undertake too much step-up and step-down conversion, which is expected to improve the overall efficiency and reliability of the system.

[0032] Reasonable current path: The current path is forced to pass through the quantum well layer to avoid current detour and ensure the normal light emission of the LED.

[0033] Uniform current distribution: A current expansion layer is set between the P-type GaN layer and the P electrode to evenly distribute the current and reduce local hot spot effects.

[0034] High process feasibility: Using existing photolithography and metal deposition processes, the bridge electrode and electrode structure design can be achieved with high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 : Schematic diagram of LED chip structure of P-GaN resistance solution.

[0036] Figure 2 : Schematic diagram of LED chip structure of N-GaN resistance solution. DETAILED DESCRIPTION

[0037] Example 1: P-GaN resistor solution

[0038] (1) Structural description

[0039] Substrate 100: provides a supporting structure to ensure the stability of the LED chip.

[0040] N-type GaN layer 200: disposed on the substrate, for conducting electrons.

[0041] MQW layer 300: disposed on the N-type GaN layer, for electron-hole recombination luminescence.

[0042] The P-type GaN layer 400 is disposed on the MQW layer and is divided into a left-side P-type GaN layer and a right-side P-type GaN layer, which are electrically isolated from each other.

[0043] P electrode 500: is disposed on the left P-type GaN layer and evenly distributes the current through the current spreading layer.

[0044] N-electrode 600: disposed on the right P-type GaN layer and electrically isolated from the left P-type GaN layer.

[0045] The bridge electrode 700 is made of metal gold (Au), connects the right P-type GaN layer and the N-type GaN layer to form a series resistor, and the distance d between the bridge electrode and the N-electrode is set to 100 micrometers.

[0046] (2) Current path

[0047] The current path is:

[0048] P electrode → P-type GaN layer on the left → MQW layer → N-type GaN layer → P-type GaN layer on the right → N electrode

[0049] (3) Process Implementation

[0050] Photolithography process: Precise photolithography is performed on the P-type GaN layer to divide the left P-type GaN layer and the right P-type GaN layer and ensure that the two are electrically isolated.

[0051] Etching process: Etching out the contact area of ​​the bridge electrode to ensure that the bridge electrode can be effectively connected to the N-type GaN layer and the right P-type GaN layer.

[0052] Metal deposition process: Metal deposition is performed in the P-electrode, N-electrode and bridge electrode areas to form a stable ohmic contact.

[0053] Current spreading layer setting: A current spreading layer is set between the left P-type GaN layer and the P electrode to ensure uniform current distribution.

[0054] (4) Test conditions

[0055] Test object: LED chip with P-GaN resistor solution.

[0056] Current injection: 20mA.

[0057] Test equipment: semiconductor parameter tester.

[0058] Test environment: room temperature 25℃, humidity 50%

[0059] Test results:

[0060] parameter Test Results Forward voltage(Vf) 4V Output current (Iout) 20mA Series resistance (Rs) 15Ω Luminous efficiency 140lm / W Hotspot Effect No significant hot spots

[0061] Example 2: N-GaN resistor solution

[0062] (1) Structural description

[0063] Substrate 100: provides a supporting structure.

[0064] N-type GaN layer 200: disposed on the substrate, for conducting electrons.

[0065] MQW layer 300: disposed on the N-type GaN layer, for electron-hole recombination luminescence.

[0066] P-type GaN layer 400: disposed on the MQW layer and covers the MQW layer.

[0067] P electrode 500: is disposed on the P-type GaN layer and evenly distributes the current through the current spreading layer.

[0068] N-electrode 600: disposed on the N-type GaN layer after the P-type GaN layer and the MQW layer are etched away.

[0069] The bridge electrode 700 is made of metal platinum (Pt) and is electrically connected only to the N-type GaN layer to form a series resistor.

[0070] (2) Current path

[0071] The current path is:

[0072] P electrode → P-type GaN layer on the left → MQW layer → N-type GaN layer → N electrode

[0073] (3) Process Implementation

[0074] Etching process: Etching is performed in the P-type GaN layer and the MQW layer to expose the N-type GaN layer.

[0075] Metal deposition process: Metal deposition is performed in the N-electrode area to ensure stable ohmic contact with the N-type GaN layer.

[0076] Bridging electrode setting: A bridging electrode is set in the etched area, connected only to the N-type GaN layer, and the distance d between the N-electrode and the N-electrode is set to 100 microns.

[0077] (4) Test conditions

[0078] Test object: LED chip with N-GaN resistor solution.

[0079] Current injection: 20mA.

[0080] Test equipment: semiconductor parameter tester.

[0081] Test environment: room temperature 25℃, humidity 50%.

[0082] (2) Test results

[0083] parameter Test Results Forward voltage(Vf) 5V Output current (Iout) 20mA Series resistance (Rs) 18Ω Luminous efficiency 135lm / W Hotspot Effect No significant hot spots

[0084] in conclusion:

[0085] Both schemes can achieve the adjustability of the series resistance. By adjusting the width spacing between the bridge electrode and the N electrode, the series resistance can be effectively changed to achieve flexible adjustment of the output voltage of the LED chip to meet the voltage requirements under different working conditions. In the P-GaN resistance scheme, the series resistance is provided by the P-type GaN layer on the right, which has higher luminous efficiency; in the N-GaN resistance scheme, the series resistance is provided by the N-type GaN layer, which has a simpler process implementation. Both schemes design reasonable current paths to ensure that the current is forced to pass through the quantum well layer (MQW), avoid bypass phenomena, and improve the luminous efficiency of the LED chip. At the same time, a current expansion layer is set between the P-type GaN layer on the left and the P electrode to ensure uniform current distribution, reduce local hot spot effects, and improve the stability and service life of the LED chip. In addition, the present invention adopts mature photolithography, etching and metal deposition processes, which can realize chip structure design with high precision, and the process is mature and feasible. The two schemes have their own advantages and are suitable for different application scenarios. They can be selected according to specific needs. The present invention effectively solves the problems existing in the existing LED chips in output voltage regulation, current path management and current distribution uniformity, and has significant technical advantages, practical value and broad promotion prospects.

[0086] The above exemplary writing is only used to illustrate the design concept of the present invention, and is not intended to limit the protection scope of the present invention. Any equivalent or modified design based on the concept of the present invention is deemed to fall within the protection scope of the present invention.

Claims

1. An LED chip with adjustable output voltage, characterized in that: include: substrate; An N-type GaN layer, a multi-quantum well (MQW) layer and a P-type GaN layer are disposed on the substrate; A P electrode disposed on the P-type GaN layer; N electrode, its position is set according to different structures: In one structure, the N electrode is disposed on a right P-type GaN layer electrically isolated from a left P-type GaN layer; In another structure, the N-electrode is disposed on the N-type GaN layer after etching away the P-type GaN layer and the multi-quantum well (MQW) layer; The connection method of the bridge electrode is set according to different structures: In one structure, the bridge electrode is electrically connected to the right P-type GaN layer and the N-type GaN layer; In another structure, the bridge electrode is electrically connected to the N-type GaN layer; There is an adjustable width interval between the bridge electrode and the N electrode to form an adjustable series resistor, and the series resistor adjusts the output voltage of the LED chip by adjusting the width interval; The current path passes through: In the structure where the N electrode is disposed on the right P-type GaN layer, the current path is: P electrode→left P-type GaN layer→multi-quantum well (MQW) layer→N-type GaN layer→right P-type GaN layer→N electrode; In the structure where the N-electrode is disposed on the etched N-type GaN layer, the current path is: P-electrode→left P-type GaN layer→multi-quantum well (MQW) layer→N-type GaN layer→N-electrode.

2. The LED chip according to claim 1, characterized in that: The bridging electrode is electrically connected to the right P-type GaN layer and the N-type GaN layer, the N-electrode is arranged on the right P-type GaN layer electrically isolated from the left P-type GaN layer, the series resistor is formed by the right P-type GaN layer, and the current path is forced to pass through the multiple quantum well (MQW) layer.

3. The LED chip according to claim 2, characterized in that: A current spreading layer is provided between the left P-type GaN layer and the P electrode to improve current distribution and reduce local current density.

4. The LED chip according to claim 1, characterized in that: The bridge electrode is electrically connected to the N-type GaN layer, the N-electrode is arranged on the N-type GaN layer after the P-type GaN layer and the multi-quantum well layer are etched away, and the series resistor is formed by the N-type GaN layer.

5. The LED chip according to claim 4, characterized in that: The N-electrode is in direct contact with the N-type GaN layer without a current spreading layer.

6. The LED chip according to claim 1, characterized in that: The adjustable width spacing is achieved through a photolithography process and a metal deposition process.

7. The LED chip according to claim 1, characterized in that: The resistance value of the series resistor is proportional to the adjustable width interval.

8. The LED chip according to claim 1, characterized in that: The bridge electrode is made of a metal material, and the metal material includes gold (Au), platinum (Pt) or titanium (Ti).

9. The LED chip according to claim 1, characterized in that: The adjustable width interval has an adjustment range of 1 μm to 100 μm.

Images