Light Conversion Device via Flip-Chip Bonding
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Solution Overview
Problem
Conventional light conversion devices face challenges in material selection and manufacturing complexity due to the need for epitaxial growth or wafer fusion, leading to low yield and limited mass production potential, as well as restricted functionality as up-converters.
Innovation Solution
A light conversion device comprising a light-emitting unit and a photoelectric conversion unit connected via an electroconductive bonding layer, produced individually and bonded using the flip-chip technique, eliminating the need for high-temperature and high-pressure conditions and complex epitaxial structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct epitaxial growth method is used to connect LED and PD, then the LED and PD can be epitaxially grown together, but the selection of materials is limited due to different band gaps and lattice matching requirements
Solution Approach 1:
The device is divided into three separate components: an LED chip, a PD chip, and a bonding layer. These components are manufactured independently with optimized materials for each function, then bonded together. This segmentation allows each component to use the most suitable materials without being constrained by lattice matching requirements between LED and PD active regions.
Solution Approach 2:
A bonding layer is introduced as an intermediary between the LED chip and PD chip. This bonding layer serves as a mediator that enables electrical connection and optical coupling between the two chips while allowing independent material optimization for each component, thus resolving the material selection limitation.
2Ease of manufacture
If wafer fusion method is used to join LED and PD epitaxial wafers, then the wafers can be bonded together, but the process requires high temperature and pressure conditions leading to low yield
Solution Approach 1:
The bonding process parameters are changed from high temperature and pressure (wafer fusion) to lower temperature and pressure conditions using a bonding layer. The bonding layer material is selected to enable reliable bonding at reduced thermal and mechanical stress, thereby improving manufacturing yield while maintaining ease of manufacture.
3Ease of manufacture
If conventional light conversion devices are produced using epitaxial growth or wafer fusion, then the devices can be manufactured, but mass production is difficult due to low yield and complex processes
Solution Approach 1:
The device is segmented into independently manufacturable LED chips and PD chips that can be produced using standard semiconductor fabrication processes. This segmentation enables parallel production and assembly, significantly improving mass production capability while maintaining manufacturing simplicity through the use of a bonding layer.
4Reliability
If direct epitaxial growth is used with different band gap materials for LED and PD active regions, then the devices can be formed, but stress and lattice matching must be carefully considered
Solution Approach 1:
The device is segmented into separate LED and PD chips with their own optimized multi-layered structures. Each chip can be designed and manufactured with appropriate stress and lattice matching for its specific materials, eliminating the need for complex stress management across a single integrated epitaxial structure.
Solution Approach 2:
The bonding layer acts as an intermediary that decouples the structural and stress constraints between LED and PD chips. This allows each chip to have independently optimized multi-layered structures without requiring complex stress and lattice matching considerations across the entire device.
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 approach allows for the production of light conversion devices that can operate as both up-converters and down-converters with improved efficiency and scalability, enabling the conversion of infrared light to visible light and vice versa, with conversion efficiencies ranging from 0.037 to 0.382 W/W.
Implementation Method 1
an electroconductive bonding layer connecting a light-emitting unit with a photoelectric conversion unit
Implementation Method 2
The photoelectric conversion unit is capable of converting an optical signal to an electrical signal when a reverse bias is applied thereto
Implementation Method 3
the light-emitting unit generates a modulated light which has a frequency different from that of the external light
Data Source
AI summary
A light conversion device includes a light-emitting unit, a photoelectric conversion unit, and an electroconductive bonding layer. Each of the light-emitting unit and the photoelectric conversion unit includes a first-type region and a second-type region opposite to the first-type region. The electroconductive bonding layer is disposed between the light-emitting unit and the photoelectric conversion unit for connecting the photoelectric conversion unit with the light-emitting unit. When the light conversion device is operated to receive a bias and an external light, the light-emitting unit generates a modulated light having a frequency different from that of the external light.