Tunnel Junction Light Emitting Device for Deep Ultraviolet Extraction
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Solution Overview
Problem
Current light emitting devices face challenges in achieving high reflectance and optical extraction efficiency, particularly for deep ultraviolet (DUV) light emission, due to limitations in semiconductor materials and electrode configurations.
Innovation Solution
The design incorporates a tunnel junction layer with a PN junction between nitride semiconductor layers, along with reflective electrodes made of aluminum or aluminum alloys, and includes recesses in the tunnel junction layer to facilitate ohmic and schottky contacts, enhancing light extraction and reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional electrode configurations are used, then device structure is simple, but reflectance and optical extraction efficiency are insufficient
Solution Approach 1:
The second electrode is divided into multiple segments with different functions: a first contact part for ohmic contact with the n-type nitride semiconductor layer, and a second contact part for schottky contact with the p-type nitride semiconductor layer. This segmentation allows each part to perform its specific function optimally, improving reflectance and optical extraction efficiency while maintaining manageable device complexity
Solution Approach 2:
Different regions of the second electrode are designed with different contact properties: the first contact part has ohmic contact characteristics for efficient current injection, while the second contact part has schottky contact characteristics for effective current blocking. This local differentiation of electrode properties enables simultaneous optimization of both light extraction and current control
2Illumination intensity
If conventional tunnel junction layers are used, then manufacturing is simpler, but optical extraction efficiency is reduced
Solution Approach 1:
The tunnel junction layer is segmented into distinct n-type and p-type nitride semiconductor layers with different doping concentrations. The n-type layer has higher doping concentration for efficient electron injection, while the p-type layer has lower doping concentration for effective hole injection and current blocking, optimizing optical extraction efficiency
Solution Approach 2:
The tunnel junction layer utilizes parameter changes in doping concentration across different nitride semiconductor layers. By varying the doping concentration from high in the n-type layer to low in the p-type layer, the structure achieves optimal electrical and optical properties for enhanced light extraction efficiency
3Illumination intensity
If light absorptivity is not controlled, then device structure is simpler, but light emission efficiency decreases
Solution Approach 1:
The patent converts the potentially harmful light absorption by the p-type nitride semiconductor layer into a beneficial current blocking function. The same layer that absorbs light is designed with specific properties to block current effectively, transforming the loss mechanism into a useful function for improving overall light emission efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves light emission efficiency and reflectance for DUV light, specifically in the 250 nm to 340 nm wavelength range, by reducing light absorptivity and promoting current blocking, thereby enhancing the overall performance of the light emitting device.
Implementation Method 1
The first electrode and the second electrode may be reflective electrodes comprising Al, Al/Ti or an Al alloy
Implementation Method 2
a portion of the second electrode is in schottky contact with the second conductive type nitride semiconductor layer through the first conductive type nitride semiconductor layer
Implementation Method 3
The second electrode may include a first contact part which is in ohmic contact with an upper surface of the first conductive type nitride semiconductor layer
Implementation Method 4
a light emitting diode (hereinafter, referred to as an 'LED') is a semiconductor device that converts an electrical signal into infrared light, visible light or other forms of light using recombination between electrons and holes
Data Source
AI summary
A light emitting device is disclosed. The light emitting device includes a first conductive type semiconductor layer, an active layer disposed on the first conductive type semiconductor layer, a tunnel junction layer comprising a second conductive type nitride semiconductor layer and a first conductive type nitride semiconductor layer disposed on the active layer, wherein the first conductive type nitride semiconductor layer and the second conductive type nitride semiconductor layer are PN junctioned, a first electrode disposed on the first conductive type semiconductor layer, and a second electrode disposed on the first conductive type nitride semiconductor layer, wherein a portion of the second electrode is in schottky contact with the second conductive type nitride semiconductor layer through the first conductive type nitride semiconductor layer.