Group III Nitride p-Cladding Layer Uniform Mg Concentration
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Solution Overview
Problem
Existing methods for forming p-cladding layers in Group III nitride semiconductor light-emitting devices result in uneven Mg concentration distribution, affecting carrier distribution and leading to suboptimal light emission performance and potential crystal defects due to overdoping.
Innovation Solution
A two-stage MOCVD process is employed to form the p-cladding layer, where the Mg dopant gas supply is reduced in the latter process to half or less than in the former process, along with adjusting the Al composition ratio and thickness to achieve uniform Mg concentration and prevent crystal defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the p-cladding layer is formed at a constant supply amount of Mg dopant gas, then the crystal growth is simplified, but the Mg concentration distribution becomes uneven, adversely affecting device characteristics
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant supply amount to a dynamic time-dependent supply amount. The Mg dopant gas supply is controlled to decrease over time according to a specific function, allowing the system to adapt during the crystal growth process and achieve uniform concentration distribution while maintaining process simplicity.
Solution Approach 2:
The patent changes the parameter of Mg dopant gas supply amount from a constant value to a time-varying value. By controlling the supply amount to decrease progressively during crystal growth, the patent achieves uniform Mg concentration distribution in the p-cladding layer, resolving the contradiction between manufacturing simplicity and concentration uniformity.
2Reliability
If the Mg concentration is high on the p-contact layer side of the p-cladding layer, then electron confinement is improved, but crystal defects occur due to overdoping
Solution Approach 1:
The patent controls the Mg concentration parameter to decrease progressively from the light-emitting layer side toward the p-contact layer side by adjusting the dopant gas supply over time. This gradual parameter change ensures adequate electron confinement while preventing overdoping-induced crystal defects in the p-contact layer region.
Solution Approach 2:
The patent applies local quality by creating a spatially varying Mg concentration profile within the p-cladding layer. The concentration is higher near the light-emitting layer for effective electron confinement and gradually decreases toward the p-contact layer to avoid overdoping defects, optimizing both regions with different local concentrations.
3Object-affected harmful factors
If the Mg concentration is low in the vicinity of the light-emitting layer side of the p-cladding layer, then crystal defects are reduced, but hole injection into the light-emitting layer is adversely affected
Solution Approach 1:
The patent implements a time-dependent Mg supply profile that results in higher Mg concentration near the light-emitting layer during early growth stages, ensuring sufficient hole injection. The concentration then gradually decreases toward the p-contact layer, preventing overdoping defects while maintaining optimal hole injection performance.
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 approach ensures uniform Mg concentration across the p-cladding layer, improving carrier distribution and reducing adverse effects on hole injection and light emission performance, thereby enhancing the overall device characteristics.
Implementation Method 1
a first p-cladding layer by MOCVD on the light-emitting layer and a latter process for forming a second p-cladding layer by MOCVD on the first p-cladding layer
Data Source
AI summary
The present invention provides a method for producing a Group III nitride semiconductor light-emitting device wherein a p-cladding layer has a uniform Mg concentration. A p-cladding layer having a superlattice structure in which AlGaN and InGaN are alternately and repeatedly deposited is formed in two stages of the former process and the latter process where the supply amount of the Mg dopant gas is different. The supply amount of the Mg dopant gas in the latter process is half or less than that in the former process. The thickness of a first p-cladding layer formed in the former process is 60% or less than that of the p-cladding layer, and 160 Å or less.