Nitride Semiconductor Light-Emitting Element With Interlayer
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Solution Overview
Problem
Existing nitride semiconductor light-emitting devices face challenges in reducing contact resistance between the n-contact layer and the n-side electrode while maintaining high external quantum efficiency, particularly for UV light-emitting devices, as conventional contact layers with low Al content absorb UV light, reducing efficiency and increasing production costs.
Innovation Solution
A nitride semiconductor light-emitting device structure featuring an n-contact layer made of Al x Ga 1-x N (0.7 ≤ x ≤ 1.0) with an interlayer of Al y Ga 1-y N (0 ≤ y ≤ 0.5) on the light-emitting layer side, and an electron blocking layer, which reduces contact resistance and prevents UV light absorption, along with a method involving sequential growth and dry etching for efficient production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact layer with low Al content (Al composition ratio ≤ 30%) is used to reduce contact resistance, then contact resistance between electrode and semiconductor is decreased, but UV light generated in light-emitting layer is absorbed by the contact layer and external quantum efficiency is decreased
Solution Approach 1:
The contact layer is segmented into two distinct layers: a lower contact layer with high Al content (0.7 ≤ x ≤ 1.0) for low contact resistance, and an upper interlayer with low Al content (0 ≤ y ≤ 0.5) that is transparent to UV light. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the contact structure are assigned different material compositions tailored to their specific functional requirements. The lower layer near the electrode uses high-Al-content material for electrical contact, while the upper layer near the light-emitting layer uses low-Al-content material for optical transparency.
2Loss of energy
If a second light-emitting layer is added to absorb UV light and emit longer wavelength light, then external quantum efficiency is maintained, but a relatively large number of layers has to be formed, thereby increasing production cost
Solution Approach 1:
The harmful UV light absorption function is extracted from the contact layer and relocated to a dedicated interlayer with specific optical properties. This interlayer is designed to be transparent to UV light while maintaining electrical functionality, separating the optical and electrical functions into distinct components.
Solution Approach 2:
An interlayer with low Al content is introduced as an intermediary between the high-Al-content contact layer and the light-emitting layer. This interlayer acts as a mediator that allows UV light to pass through without absorption while maintaining the electrical contact properties of the underlying high-Al layer.
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
The solution effectively reduces contact resistance to 10 Ω or less and maintains external quantum efficiency at 0.70 % or higher, enhancing light output power for UV light-emitting devices by minimizing UV light absorption and optimizing production efficiency.
Implementation Method 1
UV light generated in a light-emitting layer is absorbed by the contact layer and the external quantum efficiency is decreased
Implementation Method 2
contact resistance arising between a semiconductor and an electrode made of a metal material
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
An object of the present invention is to provide a nitride semiconductor light-emitting device in which contact resistance generated between an n-contact layer and an n-side electrode is effectively reduced while maintaining satisfactory external quantum efficiency, and a method of efficiently producing the nitride semiconductor light-emitting device. Specifically, the present invention characteristically provides a nitride semiconductor light-emitting device having a semiconductor laminated body including an n-type laminate, a light-emitting layer and a p-type laminate, and an n-side electrode and a p-side electrode, characterized in that: the n-type laminate includes an n-contact layer made of an AlxGa1-xN material (0.7≤x≤1.0) and an n-clad layer provided on the n-contact layer; and an interlayer made of an AlyGa1-yN material (0≤y≤0.5) is provided on a partially exposed portion, on the light-emitting layer side, of the n-contact layer.