LED Structure with Recessed P-Layer for ESD Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nitride semiconductor light emitting devices suffer from lattice mismatch and thermal expansion coefficient differences with sapphire substrates, leading to crystal defects that weaken the devices against electrical impacts and limit their electrostatic discharge (ESD) characteristics, necessitating improved structural enhancements to enhance reliability and ESD protection.
Innovation Solution
The light emitting device structure includes a first-conductivity-type semiconductor layer, an active layer with well and barrier layers, and a second-conductivity-type semiconductor layer, with a mask layer and recess portions to control crystal defects and improve ESD characteristics, and is integrated into a package with lead frames for enhanced electrical connectivity and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sapphire substrate is used for nitride semiconductor light emitting devices, then the device can be manufactured with available materials, but crystal defects occur due to lattice mismatch and thermal expansion coefficient differences
Solution Approach 1:
An AlN buffer layer is introduced as an intermediary between the sapphire substrate and the GaN active layer. This buffer layer serves as a transition medium that reduces the lattice mismatch and thermal expansion coefficient differences, thereby decreasing crystal defect density while still allowing the use of readily available sapphire substrates for manufacturing
2Device complexity
If the light emitting device structure is simplified, then manufacturing cost is reduced, but ESD protection capability is insufficient
Solution Approach 1:
The ESD protection function is merged into the existing light emitting device structure by forming an n-type semiconductor layer in the recess portion of the p-type semiconductor layer. This integrated approach provides ESD protection capability without requiring separate protection components, thereby maintaining structure simplicity while improving reliability
3Reliability
If crystal defects are reduced through better substrate matching, then ESD characteristics improve, but manufacturing complexity increases due to lack of commercially available lattice-matched substrates
Solution Approach 1:
The AlN buffer layer acts as a mediator that enables the use of conventional sapphire substrates while achieving reduced crystal defects. This approach improves ESD characteristics without requiring complex manufacturing processes or specialized lattice-matched substrates, thereby avoiding increased manufacturing complexity
Data Source
AI summary
A light emitting diode is disclosed. The disclosed light emitting diode includes a light emitting structure including a first-conductivity-type semiconductor layer, an active layer, and a second-conductivity-type semiconductor layer. The first-conductivity-type semiconductor layer, active layer, and second-conductivity-type semiconductor layer are disposed to be adjacent to one another in a same direction. The active layer includes well and barrier layers alternately stacked at least one time. The well layer has a narrower energy bandgap than the barrier layer. The light emitting diode also includes a mask layer disposed in the first-conductivity-type semiconductor layer, a first electrode disposed on the first-conductivity-type semiconductor layer, and a second electrode disposed on the second-conductivity-type semiconductor layer. The first-conductivity-type semiconductor layer is formed with at least one recess portion.