Oxidized Metal Contacts for Transparent LED Electrodes
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Solution Overview
Problem
Current light emitting diodes (LEDs) for direct view displays face challenges in achieving efficient multicolor emission without the need for backlight units or liquid crystals, particularly in forming LEDs with different peak wavelengths on a single semiconductor substrate.
Innovation Solution
The method involves forming a light emitting diode with a doped compound semiconductor layer, a growth mask layer, a semiconductor core, an active region, and a transparent conductive layer comprising nickel oxide, along with a reflector layer, to create nanowire-based LEDs that emit light of specific wavelengths, and bonding these LEDs to a backplane for a direct view display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional LED structures with metal contacts are used, then electrical conductivity is achieved, but light transmission is blocked due to opaque metal layers
Solution Approach 1:
The patent changes the physical and chemical parameters of the contact layer by oxidizing metal layers (nickel, copper, or aluminum) to form transparent conductive metal oxides. This oxidation process transforms opaque metals into transparent conducting materials, simultaneously achieving both light transmission and electrical conductivity requirements for LED operation.
Solution Approach 2:
The patent creates composite structures by forming metal oxide layers that combine the transparency of oxides with the conductivity of metals. The transparent conductive metal oxide layers serve as composite materials that integrate both optical transparency and electrical conductivity properties needed for the LED contact structure.
2Productivity
If multiple LEDs with different peak wavelengths are formed on a single substrate, then device integration is improved, but manufacturing precision becomes more challenging
Solution Approach 1:
The patent applies local quality by forming LEDs with different compositions and structures at different locations on the same substrate. Each LED region is locally optimized for its specific peak wavelength through controlled variation of semiconductor layer composition, thickness, and doping, while using a uniform oxidized metal contact structure across all devices.
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 enables the creation of multicolor direct view displays with efficient light emission across different wavelengths, eliminating the need for backlights and liquid crystals, and allowing for the formation of LEDs with varied peak wavelengths on a single substrate.
Implementation Method 1
oxidizing the nickel layer at an elevated temperature to form transparent conductive layer comprising nickel oxide
Implementation Method 2
diffusing the gold layer into the second conductivity type semiconductor material layer through the nickel layer during the step of oxidizing
Implementation Method 3
nanowire-based light emitting diodes employing oxidized metal contacts that emit light of different peak wavelengths
Data Source
AI summary
A method of forming a light emitting device includes forming a semiconductor light emitting diode, forming a metal layer stack including a first metal layer and a second metal layer on the light emitting diode, and oxidizing the metal layer stack to form transparent conductive layer including at least one conductive metal oxide.