LED chip with adjustable output voltage

Abstract

The application discloses an LED chip with adjustable output voltage, comprising a P-GaN resistance scheme and an N-GaN resistance scheme. In the P-GaN scheme, the N electrode is arranged on the right P-type GaN layer, the bridge electrode is connected with the right P-type GaN layer and the N-type GaN layer, and the series resistance is provided by the right P-type GaN layer; in the N-GaN scheme, the N electrode is arranged on the etched N-type GaN layer, the bridge electrode is connected with the N-type GaN layer only, and the series resistance is provided by the N-type GaN layer. The width spacing between the bridge electrode and the N electrode is adjusted in the two schemes, so that the series resistance is adjustable, and the output voltage is flexibly controlled. The application adopts photolithography process, etching process and metal deposition process, is mature and reliable, is suitable for different scenes, has the advantages of adjustable output voltage, clear current path, uniform current distribution and the like, and has significant practical value and popularization prospect.

Description

Technical Field

[0001] This invention relates to the field of semiconductor lighting technology, and more specifically, to an LED chip in which the output voltage is adjusted by connecting a GaN resistor in series inside the LED chip. Background Technology

[0002] LEDs (Light Emitting Diodes) typically consist of a P-GaN layer, a multiple quantum well (MQW) active region, and an N-GaN layer. The forward voltage of a conventional LED chip generally ranges from 1.8 to 3.6V. To obtain higher or specific voltages (e.g., 4V, 5V, 7V), multiple LED chips are usually connected in series to achieve a high voltage output that is a multiple of 3V. However, this series connection method is difficult to flexibly obtain non-multiple voltages, which has significant 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 circuitry but may also cause overheating problems at high power levels, thereby affecting the stability and reliability of the LED chip. Furthermore, while external circuits (such as Buck / Boost power conversion schemes) can achieve some voltage regulation, they are often accompanied by energy loss and increased cost.

[0004] Therefore, there is an urgent need to implement more flexible voltage regulation within LED chips to alleviate the pressure of external power management, reduce system complexity, and meet various non-standard voltage requirements. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing LED chips that cannot flexibly adjust the output voltage internally. By introducing an adjustable GaN resistor into the LED chip, the output voltage can be finely adjusted. While maintaining the main luminous efficiency of the LED, it can meet the different voltage requirements of different terminal applications and reduce the 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 multiple quantum well (MQW) layer, and a P-type GaN layer are disposed on the substrate;

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

[0011] The position of the N electrode varies depending on the specific structure:

[0012] In one configuration, the N electrode is disposed on a right-side P-type GaN layer that is electrically isolated from the left-side P-type GaN layer.

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

[0014] The connection method of the bridging electrode varies depending on the structure:

[0015] In one configuration, the bridging electrode is electrically connected to the right-side P-type GaN layer and the N-type GaN layer.

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

[0017] The bridging electrode and the N electrode have an adjustable width spacing to form an adjustable series resistor, and the output voltage of the LED chip is adjusted by adjusting the width spacing of the series resistor.

[0018] The current path passes through the following in sequence:

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

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

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

[0023] The bridging electrode is electrically connected to the N-type GaN layer. The N-electrode is disposed on the N-type GaN layer after the P-type GaN layer and the multiple quantum well layer have been etched away. The series resistance 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 photolithography and metal deposition processes.

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

[0027] The bridging electrode is made of a metallic material, including gold (Au), platinum (Pt), or titanium (Ti).

[0028] The adjustable width spacing can be adjusted from 1 μm to 100 μm.

[0029] The present invention provides two technical solutions for an LED chip with adjustable output voltage: In the P-GaN resistor solution, the N-electrode is disposed on the right-side P-type GaN layer, and a bridging electrode connects the right-side P-type GaN layer and the N-type GaN layer. The current path is P-electrode → left-side P-type GaN layer → quantum well layer (MQW) → N-type GaN layer → right-side P-type GaN layer → N-electrode, with the series resistance provided by the right-side P-type GaN layer. In the N-GaN resistor solution, the N-electrode is disposed on the etched N-type GaN layer, and the bridging electrode connects only to the N-type GaN layer. The current path is P-electrode → left-side P-type GaN layer → quantum well layer (MQW) → N-type GaN layer → N-electrode, with the series resistance provided by the N-type GaN layer. Both solutions achieve flexible adjustment of the output voltage through adjustable series resistance, ensure that the current path is forced through the quantum well layer, and provide a current spreading layer between the P-type GaN layer and the P-electrode to ensure uniform current distribution, reduce hotspot 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 adjusted. Non-multiple voltage output can be achieved within the structure of a single LED chip, avoiding a large number of series and parallel connections or external circuit modifications. This not only simplifies system design but also provides greater flexibility. The external power management unit does not need to handle too much buck-boost conversion, which is expected to improve the overall efficiency and reliability of the system.

[0032] Reasonable current path: The current path is forced through the quantum well layer to avoid current detours and ensure that the LED emits light normally.

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

[0034] High process feasibility: By utilizing existing photolithography and metal deposition processes, bridging electrodes and electrode structure designs can be realized with high precision. Attached Figure Description

[0035] Figure 1 : Schematic diagram of LED chip structure using P-GaN resistor scheme.

[0036] Figure 2 : Schematic diagram of LED chip structure using N-GaN resistor scheme. Detailed Implementation

[0037] Example 1: P-GaN Resistor Scheme

[0038] (1) Structural description

[0039] Substrate 100: Provides a support 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: Located on the N-type GaN layer, used for electron-hole recombination luminescence.

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

[0043] P-electrode 500: It is set on the left-side P-type GaN layer, and the current is uniformly distributed through the current spreading layer.

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

[0045] Bridge electrode 700: Made of metallic gold (Au), it connects the right-side P-type GaN layer and N-type GaN layer to form a series resistor, and the distance d between it and the N electrode is set to 100 micrometers.

[0046] (2) Current path

[0047] The current path is:

[0048] P-electrode → Left P-type GaN layer → MQW layer → N-type GaN layer → Right P-type GaN layer → N-electrode

[0049] (3) Process Implementation

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

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

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

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

[0054] (4) Test conditions

[0055] Test subject: LED chip with P-GaN resistor scheme.

[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 hotspots

[0061] Example 2: N-GaN Resistor Scheme

[0062] (1) Structural description

[0063] Substrate 100: Provides a support structure.

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

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

[0066] P-type GaN layer 400: Set on the MQW layer, covering the MQW layer.

[0067] P-electrode 500: It is disposed on the P-type GaN layer, and the current is uniformly distributed through the current spreading layer.

[0068] N-electrode 600: is placed on the N-type GaN layer after the P-type GaN layer and MQW layer have been etched away.

[0069] Bridge electrode 700: Made of platinum (Pt), it 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 → Left P-type GaN layer → 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 MQW layer to expose the N-type GaN layer.

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

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

[0077] (4) Test conditions

[0078] Test subject: LED chip with N-GaN resistor scheme.

[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 hotspots

[0084] in conclusion:

[0085] Both schemes enable adjustable series resistance. By adjusting the width spacing between the bridging electrode and the N electrode, the series resistance can be effectively changed, allowing for flexible adjustment of the LED chip's output voltage to meet voltage requirements under different operating conditions. In the P-GaN resistor scheme, the series resistance is provided by the right-side P-type GaN layer, resulting in higher luminous efficiency. In the N-GaN resistor scheme, the series resistance is provided by the N-type GaN layer, offering simpler process implementation. Both schemes feature well-designed current paths to ensure forced current flow through the quantum well (MQW) layer, avoiding bypass phenomena and improving the LED chip's luminous efficiency. Simultaneously, a current spreading layer is placed between the left-side P-type GaN layer and the P electrode to ensure uniform current distribution, reduce local hotspot effects, and improve the LED chip's stability and lifespan. Furthermore, this invention employs mature photolithography, etching, and metal deposition processes, enabling high-precision chip structure design; the processes are mature and feasible. Each scheme has its advantages and is suitable for different application scenarios, allowing for selection based on specific needs. This invention effectively solves the problems existing in LED chips in terms of output voltage regulation, current path management and current distribution uniformity, and has significant technical advantages, practical value and broad prospects for promotion.

[0086] The above exemplary descriptions are merely for illustrating the design concept of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalents or modifications made based on the concept of the present invention are considered to fall within the scope of protection of the present invention.

Claims

1. An LED chip with adjustable output voltage, characterized in that, include: Substrate; An N-type GaN layer, a multiple quantum well (MQW) layer, and a P-type GaN layer are disposed on the substrate; A P-electrode is disposed on the P-type GaN layer; The position of the N electrode varies depending on the specific structure: In one configuration, the N electrode is disposed on a right-side P-type GaN layer that is electrically isolated from the left-side P-type GaN layer. In another structure, the N electrode is disposed on the N-type GaN layer after the P-type GaN layer and the multiple quantum well (MQW) layer have been etched away; The connection method of the bridging electrode varies depending on the structure: In one configuration, the bridging electrode is electrically connected to the right-side P-type GaN layer and the N-type GaN layer. In another configuration, the bridging electrode is electrically connected to the N-type GaN layer; The bridging electrode and the N electrode have an adjustable width spacing to form an adjustable series resistor, and the output voltage of the LED chip is adjusted by adjusting the width spacing of the series resistor. The current path passes through the following in sequence: In the structure where the N electrode is disposed on the right-side P-type GaN layer, the current path is: P electrode → left-side P-type GaN layer → multiple quantum well (MQW) layer → N-type GaN layer → right-side 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 → multiple 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-side P-type GaN layer and the N-type GaN layer. The N-electrode is disposed on the right-side P-type GaN layer, which is electrically isolated from the left-side P-type GaN layer. The series resistance is formed by the right-side P-type GaN layer, and the current path is forced 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-side 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 bridging electrode is electrically connected to the N-type GaN layer. The N-electrode is disposed on the N-type GaN layer after the P-type GaN layer and the multiple quantum well layer have been etched away. The series resistance 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 photolithography and metal deposition processes.

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

8. The LED chip according to claim 1, characterized in that, The bridging electrode is made of a metallic material, including gold (Au), platinum (Pt), or titanium (Ti).

9. The LED chip according to claim 1, characterized in that, The adjustable width spacing can be adjusted from 1 μm to 100 μm.

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