Beryllium-Doped GaN LED p-Type Layer for Lower Resistivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
GaN-based LEDs suffer from high resistivity p-type regions, which limit their efficiency due to deep binding energy and passivation with atomic hydrogen, making it difficult to achieve low resistivity p-type materials using traditional dopants like magnesium.
Innovation Solution
Incorporating beryllium as a p-type dopant in gallium and nitrogen containing materials, such as GaN, AlGaN, and InGaN, through ion implantation and a three-step annealing process, including a high-temperature pulsed laser anneal, to activate beryllium atoms and reduce resistivity, thereby increasing hole concentration and improving electron confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional dopants like magnesium are used in GaN-based LEDs, then the doping process is simpler, but the resistivity remains high due to deep binding energy and passivation with atomic hydrogen
Solution Approach 1:
The patent changes the dopant element from magnesium to beryllium, fundamentally altering the doping parameters. Beryllium has shallower binding energy levels in GaN compared to magnesium, which directly addresses the high resistivity issue. This parameter change enables achieving lower resistivity (improving electrical conductivity) while the ion implantation and annealing process manages the manufacturing complexity.
Solution Approach 2:
The patent replaces the conventional thermal diffusion doping method with ion implantation followed by pulsed laser annealing. This substitution allows precise control of dopant depth and concentration, and the rapid heating/cooling cycle prevents excessive hydrogen diffusion, thereby reducing passivation effects and improving electrical conductivity while maintaining manufacturing feasibility.
2Reliability
If high temperature annealing is performed to activate beryllium dopant, then hole concentration increases and resistivity decreases, but nitrogen loss and crystal damage may occur
Solution Approach 1:
The patent employs pulsed laser annealing instead of continuous high-temperature heating. The pulsed nature delivers rapid, intense heat that activates beryllium dopants and increases hole concentration, followed by equally rapid cooling that prevents excessive nitrogen loss and minimizes crystal damage. This periodic thermal action resolves the contradiction between achieving high hole concentration and preventing harmful side effects.
Solution Approach 2:
The pulsed laser annealing process rushes through the critical temperature window where nitrogen loss occurs. By heating to the required temperature for brief periods and immediately cooling, the process achieves dopant activation without allowing sufficient time for significant nitrogen diffusion and loss, thereby maintaining crystal integrity while improving hole concentration.
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 use of beryllium as a p-type dopant results in a significant reduction in resistivity, leading to higher efficiency with less efficiency droop, lower operating voltages, and increased emission intensity, potentially improving LED performance by up to 20%.
Implementation Method 1
subjecting the region of the semiconductor substrate using a pulsed laser to achieve a surface temperature greater than 1000 degrees Celsius for a time period of shorter than one second
Implementation Method 2
introducing a plurality of impurities into a region of the semiconductor substrate using an ion implantation process
Implementation Method 3
the implanted beryllium atoms are activated within the region configured by a high temperature annealing process to form a low resistivity p-type layer
Data Source
AI summary
The invention described herein provides a method and apparatus to realize incorporation of Beryllium followed by activation to realize p-type materials of lower resistivity than is possible with Magnesium. Lower contact resistances and more effective electron confinement results from the higher hole concentrations made possible with this invention. The result is a higher efficiency GaN-based LED with higher current handling capability resulting in a brighter device of the same area.