Semiconductor Chip Transparent Conductive Layer Blue Radiation
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Solution Overview
Problem
Conventional light-emitting semiconductor chips and optoelectronic components suffer from poor reflectivity of metallic contacts, leading to optical losses and reduced efficiency, particularly in the blue region, due to full-surface metallization causing radiation reflection and absorption.
Innovation Solution
The design features a light-emitting semiconductor chip with a radiation-transmissive substrate and a transparent, electrically conductive layer, along with strategically positioned and smaller metallic contacts, and wavelength conversion using phosphors to minimize blue radiation reflection, allowing more efficient emission and reduced absorption losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-surface metallization is used for electrical contacting, then electrical connection is improved, but optical losses increase due to poor reflectivity of metallic contacts
Solution Approach 1:
The contact structure is segmented into multiple functional layers: a transparent electrically conductive layer for current injection and metallic contact layers for electrical connection. This segmentation allows each layer to perform its specific function optimally without compromising the other, resolving the contradiction between electrical connection reliability and optical loss reduction.
Solution Approach 2:
Different regions of the contact structure have different optical properties. The transparent electrically conductive layer is positioned where optical transmission is needed, while metallic contacts are placed in regions where their reflectivity is less critical. This local differentiation of material properties allows simultaneous optimization of electrical connection and optical performance.
2Reliability
If metallic contacts are used for electrical contacting, then electrical conductivity is improved, but blue radiation reflection and absorption increase
Solution Approach 1:
A transparent electrically conductive layer is introduced as an intermediary between the semiconductor layer sequence and the metallic contacts. This intermediary layer has high transparency in the blue spectral range, allowing blue radiation to pass through without being reflected or absorbed by the metallic contacts, while still providing the necessary electrical conductivity for current injection.
Solution Approach 2:
The contact structure uses composite materials combining transparent electrically conductive oxides (such as ITO or FTO) with metallic layers. This composite structure integrates the optical transparency of the oxide layer with the electrical conductivity of the metal layer, resolving the contradiction between electrical performance and optical transparency in the blue range.
3Loss of energy
If substrate transmittance is increased to improve light extraction, then optical efficiency is improved, but substrate material selection becomes more restricted
Solution Approach 1:
The device uses composite material structures including the semiconductor layer sequence grown on the substrate, transparent electrically conductive oxide layers, and metallic contact layers. This composite approach allows the substrate to be optimized for mechanical support and thermal management while the transparent conductive layers and contact structures are optimized for optical performance in the blue spectral range.
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 configuration enhances the efficiency of the semiconductor chip and optoelectronic component by reducing reflection and absorption losses, increasing the proportion of converted radiation and improving mechanical and thermal stress management.
Implementation Method 1
The transparent, electrically conductive layer is electrically connected to the first contact
Implementation Method 2
the electrically conductive layer has a transmittance of at least 60%, 70%, 80% or at least 90% with respect to a wavelength of the electromagnetic radiation
Implementation Method 3
the semiconductor layer sequence is configured to emit the electromagnetic radiation in the visible, ultraviolet or infrared spectral range
Implementation Method 4
During operation of the semiconductor chip, the semiconductor layer sequence is in particular configured to emit the electromagnetic radiation
Implementation Method 5
The first and/or the second contact are each designed to be reflective at least on a side facing the substrate, in particular for the radiation emitted by the semiconductor layer sequence
Implementation Method 6
the substrate has a transmittance of at least 60%, 70%, 80% or at least 90% with respect to a wavelength of the electromagnetic radiation generated during operation of the semiconductor chip
Data Source
AI summary
A light-emitting semiconductor chip comprises: a radiation-transmissive substrate, an epitaxially grown semiconductor layer sequence on a main surface of the substrate, a first contact and a second contact on a contact surface of the semiconductor layer sequence facing away from the substrate for electrical and mechanical contacting of the semiconductor chip, a transparent, electrically conductive layer which is arranged on the contact side and is electrically connected to the first contact.