Semipolar Nitride Films via Indium Buffer MOCVD
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Solution Overview
Problem
Current nitride technology for electronic and optoelectronic devices grown along polar c-directions suffers from strong piezoelectric and spontaneous polarizations, leading to reduced carrier recombination efficiency and emission, and the growth of nonpolar and semipolar nitrides is challenging, with limited adoption in the industry.
Innovation Solution
A method for growing device-quality planar semipolar nitride semiconductor thin films using a metalorganic chemical vapor deposition (MOCVD) process with an (Al,In,Ga)N nucleation or buffer layer containing indium, allowing for the deposition of semipolar (Ga,Al,In,B)N films with a large usable area parallel to the substrate surface, reducing polarization effects and improving crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nitride technology is grown along polar c-directions, then the growth process is well-established and easier to manufacture, but strong piezoelectric and spontaneous polarizations occur leading to reduced carrier recombination efficiency and emission
Solution Approach 1:
The patent changes the crystallographic orientation parameter from polar c-direction to semipolar directions, which fundamentally alters the polarization characteristics while maintaining compatibility with established MOCVD growth processes
Solution Approach 2:
The patent employs composite layer structures including AlInGaN buffer layers and InGaN quantum wells grown on semipolar orientations, combining different materials with complementary properties to achieve both ease of manufacture and improved device performance
2Reliability
If nonpolar and semipolar nitrides are grown to reduce polarization effects, then carrier recombination efficiency is improved, but the growth process becomes more challenging and has limited industry adoption
Solution Approach 1:
The patent introduces AlInGaN buffer layers as intermediary structures that facilitate the transition from standard c-plane substrates to semipolar growth orientations, making the challenging semipolar growth process more manageable and industrially viable
Solution Approach 2:
The patent performs preliminary buffer layer growth and surface preparation steps before the main device layer growth, preparing the substrate and interface in advance to enable successful semipolar growth and reduce process complexity
3Reliability
If semipolar nitride films are grown to reduce built-in electric fields, then internal quantum efficiency is enhanced, but the available surface area for device processing is limited
Solution Approach 1:
The patent transitions from two-dimensional lateral expansion constraints to three-dimensional controlled growth on semipolar facets, enabling both high efficiency and adequate processing area through vertical growth control
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 method enables the growth of smooth planar semipolar nitride films with reduced crystallographic defects and improved surface morphology, enhancing the internal quantum efficiency of nitride optoelectronic devices by reducing built-in electric fields and increasing the available surface area for device processing.
Implementation Method 1
A method for growing device-quality planar semipolar nitride semiconductor thin films using a metalorganic chemical vapor deposition (MOCVD) process
Implementation Method 2
metalorganic chemical vapor deposition (MOCVD) process
Data Source
AI summary
A method for enhancing growth of device-quality planar semipolar nitride semiconductor thin films via metalorganic chemical vapor deposition (MOCVD) by using an (Al,In,Ga)N nucleation layer containing at least some indium. Specifically, the method comprises loading a substrate into a reactor, heating the substrate under a flow of nitrogen and/or hydrogen and/or ammonia, depositing an InxGa1-xN nucleation layer on the heated substrate, depositing a semipolar nitride semiconductor thin film on the InxGa1-xN nucleation layer, and cooling the substrate under a nitrogen overpressure.