Group III Nitride LED Ag Reflective Film Migration Prevention
Solution Overview
Problem
Ag or Ag alloy reflective films in Group III nitride semiconductor light-emitting devices experience migration due to potential differences between electrodes, despite being enclosed within insulating films.
Innovation Solution
A conductive film is formed between the n-lead electrode and the reflective film, electrically connected to the p-contact or p-type layer, creating an equipotential region to prevent migration, with materials like Al, Ti, or ITO used for the conductive film and p-contact electrodes for improved adhesion and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflective film is enclosed in an insulating film to prevent Ag migration, then reliability is improved, but migration still occurs in regions between electrodes due to potential difference
Solution Approach 1:
The patent applies the equipotentiality principle by introducing a conductive film connected to the p-type layer or p-contact electrode, which equalizes the potential in the region between the n-lead electrode and p-electrode. This eliminates the potential difference that drives Ag migration, thereby preventing migration while maintaining the insulating film's protective enclosure. The conductive film creates an equipotential region that counteracts the harmful electric field.
2Reliability
If a conductive film is added to create an equipotential region, then Ag migration is prevented, but device complexity increases
Solution Approach 1:
The conductive film serves multiple functions: it creates an equipotential region to prevent Ag migration, maintains electrical connection to the p-type layer or p-contact electrode, and integrates within the existing insulating film structure. By combining these functions in a single component, the patent avoids adding multiple separate elements, thereby limiting the increase in device complexity while achieving reliable migration prevention.
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 conductive film effectively prevents Ag migration by maintaining an equipotential region, enhancing the stability and light extraction performance of the reflective film, particularly in flip-chip-type devices.
Implementation Method 1
a conductive film is formed via the insulating film between the n-lead electrode and the reflective film of the region, and the conductive film is electrically connected to at least one of the p-contact electrode and the p-type layer
Implementation Method 2
the light emitted from a light-emitting layer to a p-type layer side is reflected to an n-type layer side by the reflective film, and thereby light extraction performance is improved
Data Source
AI summary
A Group III nitride semiconductor light-emitting device having an Ag or Ag alloy reflective film provided in an insulating film, at least a portion of the reflective film is located via the insulating film in a region between an n-lead electrode and at least one of a p-contact electrode having transparency and a p-type layer, wherein a conductive film is formed via the insulating film between the n-lead electrode and the reflective film of the region, and the conductive film is electrically connected to at least one of the p-contact electrode and the p-type layer.