LED Electrode Layout With Widened Current Blocking Layer for ESD
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Solution Overview
Problem
Conventional light-emitting devices with nitride-based semiconductor epitaxial structures suffer from current crowding and electrostatic discharge (ESD) issues due to non-uniform current distribution and alignment errors in the current blocking layer, leading to poor ESD resistance and high burnout rates.
Innovation Solution
A light-emitting device design featuring a current blocking layer with a widened section beneath the first electrode extension portion, which gradually increases in width away from the electrode pad, and a transparent conductive layer to facilitate uniform current spreading and reduce charge concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional current blocking layer with fixed width is used beneath the first electrode extension, then the structure is simple and easy to manufacture, but current crowding occurs at the electrode end and ESD resistance is poor
Solution Approach 1:
The current blocking layer is designed with non-uniform width: a first width beneath the electrode pad extension and a second width (greater than the first) beneath the electrode end portion. This local variation in geometry optimizes current distribution at different locations, preventing charge concentration at the electrode end while maintaining simple manufacturing processes.
2Reliability
If the first electrode extension is formed as a polyline or curve to improve current spreading, then current distribution may be improved, but alignment offset with the current blocking layer becomes more serious and burnout risk increases
Solution Approach 1:
The current blocking layer width is locally increased beneath the electrode end portion where alignment offset and charge concentration are most problematic. This compensates for the misalignment effects and prevents burnout even when the electrode extension has complex geometry for current spreading.
Solution Approach 2:
The wider current blocking layer beneath the electrode end portion acts as a pre-designed protective region that cushions against the harmful effects of alignment offset and charge concentration before they can cause burnout during ESD events.
3Reliability
If the current blocking layer has a larger area to block current vertically, then current spreading is improved, but charge concentration occurs at the electrode end and burnout is more likely
Solution Approach 1:
The current blocking layer is designed with spatially varying width to balance two opposing requirements: sufficient area for current blocking and spreading, while avoiding excessive width that would cause charge concentration at the electrode end. The width transitions from a first value beneath the pad extension to a second (larger) value beneath the electrode end, optimizing both functions locally.
Data Source
AI summary
A light-emitting device includes first and second type semiconductor layers, an active layer interposed therebetween, a current blocking layer disposed on the first type semiconductor layer and including a first strip portion, and a first electrode disposed on the current blocking layer and including a first electrode pad, a first electrode end portion distal from the first electrode pad, and a first electrode extension portion extending between the first electrode pad and the first electrode end portion. The first strip portion of the current blocking layer is located beneath the first electrode extension portion, and has a widened section having a width that gradually increases in a direction away from the first electrode pad.