Semiconductor LED Transparent Oxide Mirror Interface
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Solution Overview
Problem
Current semiconductor light-emitting diodes have limited light yield due to inefficient reflection of electromagnetic radiation at the mirror layer, primarily because of high roughness at the interface between the oxide and mirror layers, which affects the reflection of radiation components at large angles of incidence.
Innovation Solution
A semiconductor light-emitting diode is designed with an oxide layer made of transparent conductive oxide and a mirror layer, where the second interface of the oxide layer has a roughness of less than 1.0 nm, achieved through HF-assisted DC sputtering, and a p-doped semiconductor layer is used to protect the light-emitting diode layer from damage during oxide deposition, with a tunnel contact formed by undoped and n-doped semiconductor layers to reduce operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mirror layer is provided behind the semiconductor layer stack to reflect radiation back in the emission direction, then the light yield is improved, but the reflection efficiency is reduced due to high roughness at the oxide-mirror layer interface
Solution Approach 1:
The patent applies preliminary action by depositing the oxide layer with controlled roughness parameters before depositing the mirror layer, ensuring that the interface is prepared in advance to optimize reflection. The oxide layer is deposited with a specific roughness profile (Ra < 0.5 nm) that preconditions the surface for high-quality mirror layer adhesion and reflection, preventing subsequent degradation of reflection efficiency.
Solution Approach 2:
The patent changes the physical parameters of the oxide layer, specifically controlling its roughness (Ra < 0.5 nm) and thickness (5-50 nm), to optimize the interface for mirror layer deposition. By adjusting these parameters during the deposition process, the invention achieves both good adhesion and high reflection efficiency, resolving the contradiction between light yield and interface quality.
2Manufacturing precision
If the oxide layer is made thicker to level out unevenness from the semiconductor layer, then the interface roughness is improved, but the operating voltage increases due to higher impedance
Solution Approach 1:
The patent optimizes the oxide layer thickness to a specific range (5-50 nm) that balances two competing requirements: thick enough to level out surface unevenness and achieve Ra < 0.5 nm, but thin enough to maintain low electrical impedance. This precise parameter control allows the oxide layer to serve both as a surface-smoothing layer and as an electrical contact layer.
Solution Approach 2:
The patent uses a composite structure consisting of the oxide layer combined with the mirror layer and underlying semiconductor layers. The oxide layer acts as an intermediate layer with specific optical and electrical properties that bridge the semiconductor layer and mirror layer, achieving both surface smoothing and electrical conductivity in a single integrated structure.
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 low roughness of the oxide layer's second interface enhances the reflection of electromagnetic radiation, increasing the light yield of the semiconductor light-emitting diode by ensuring that radiation components at large angles of incidence are reflected more effectively, thereby improving the overall intensity of emitted radiation.
Implementation Method 1
an oxide layer made of a transparent conductive oxide and one or more mirror layers are provided behind the semiconductor layer stack. The electromagnetic radiation impinging on the mirror layers is reflected to a proportion that depends on the difference in the optical refractive indices of the layers
Implementation Method 2
achieved through HF-assisted DC sputtering
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A semiconductor light-emitting diode (10) is proposed having at least one p-doped light-emitting diode layer (4), an n-doped light-emitting diode layer (2) and an optically active zone (3) between the p-doped light-emitting diode layer (4) and the n-doped light-emitting diode layer (2), having an oxide layer (8) consisting of a transparent conductive oxide, and having at least one mirror layer (9), wherein the oxide layer (8) is disposed between the light-emitting diode layers (2, 4) and the at least one mirror layer (9), and comprises a first boundary surface (8a) which faces the light-emitting diode layers (2, 4) and a second boundary surface (8b) which faces the at least one mirror layer (9), and wherein the second boundary surface (8b) of the oxide layer (8) has less roughness (R2) than the first boundary surface (8a) of the oxide layer (8).