Nitride-Based Light-Emitting Device With Graded Electron Barrier
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Solution Overview
Problem
Current nitride-based light-emitting devices face challenges in reducing waveguide loss, suppressing leakage current, and lowering operating voltage, particularly in high-temperature operations, as existing solutions do not effectively manage the piezoelectric field-induced band structure changes and doping concentration profiles.
Innovation Solution
A nitride-based light-emitting device structure is implemented with a GaN substrate, featuring a nitride-based semiconductor active layer, electron barrier layers with varying Al composition, and impurity concentration gradients to control the piezoelectric field and doping profiles, specifically including an electron barrier layer with an Al composition that increases from the active layer to the second-conductivity-side semiconductor layer, and a low-doped region in the P-type AlGaN cladding layer to reduce waveguide loss and operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an electron barrier layer with high Al composition is used to suppress leakage current, then leakage current is reduced, but waveguide loss increases
Solution Approach 1:
The electron barrier layer employs a graded Al composition structure where the Al content varies spatially: higher Al composition near the active layer interface to maximize electron blocking, and lower Al composition toward the cladding layer to minimize waveguide loss. This local variation in material composition optimizes both leakage suppression and light confinement simultaneously.
Solution Approach 2:
The Al composition parameter in the electron barrier layer is changed gradually from the active layer interface toward the cladding layer. This parameter gradient allows continuous optimization of the balance between electron barrier height (for leakage suppression) and refractive index contrast (for waveguide loss reduction).
2Power
If high doping concentration is used in the P-type cladding layer to reduce operating voltage, then operating voltage is reduced, but waveguide loss increases
Solution Approach 1:
The P-type cladding layer employs a graded doping concentration structure where the doping level varies spatially: higher doping concentration near the contact layer to reduce series resistance and operating voltage, and lower doping concentration near the active layer interface to minimize free-carrier absorption and waveguide loss. This local variation in electrical properties optimizes both voltage reduction and light confinement.
Solution Approach 2:
The doping concentration parameter in the P-type cladding layer is changed gradually from the contact layer toward the active layer interface. This parameter gradient allows continuous optimization of the balance between electrical conductivity (for voltage reduction) and optical transparency (for waveguide loss reduction).
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 achieves reduced waveguide loss, suppressed leakage current, and lower operating voltage, enabling reliable high-power, low-temperature operation by effectively managing the band structure and doping concentrations, thus enhancing the device's efficiency and reliability.
Implementation Method 1
manage the piezoelectric field-induced band structure changes
Implementation Method 2
an active layer including a nitride-based semiconductor containing Ga or In
Data Source
AI summary
A nitride-based light-emitting device includes, on a GaN substrate: a first-conductivity-side first semiconductor layer; an active layer; and a second-conductivity-side first semiconductor layer, in the stated order, and further includes an electron barrier layer of a second conductivity type between the active layer and the second-conductivity-side first semiconductor layer, the electron barrier layer including a nitride-based semiconductor containing at least Al. The electron barrier layer has a first region in which an Al composition changes. The Al composition in the first region monotonically increases in a direction from the active layer to the second-conductivity-side first semiconductor layer. An impurity concentration in the second-conductivity-side first semiconductor layer is lower in a region nearer the electron barrier layer than in a region farther from the electron barrier layer.