Multiple Quantum Well Structure With Binary Layer Segmentation
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Solution Overview
Problem
The challenge in fabricating semiconductor structures with multiple quantum wells using indium phosphide (InP) is the occurrence of morphological defects, such as undulations, which limit the number of quantum wells that can be grown in a stack, leading to potential device failures and reduced efficiency in optoelectronic devices.
Innovation Solution
A method involving the deposition of a third binary semiconductor layer with a matching lattice constant to the substrate, followed by additional stacks of quantum wells, allows for the growth of thicker stacks without introducing strain or modifying existing fabrication processes, thereby reducing defects and increasing the number of InP-containing quantum wells that can be fabricated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple quantum wells are grown in a stack using InP, then the optical confinement and device efficiency are improved, but morphological defects such as undulations occur, limiting the number of quantum wells that can be fabricated
Solution Approach 1:
The patent divides the continuous stack of quantum wells into segments separated by binary semiconductor layers. These intermediate layers act as segmentation boundaries that reset the morphological structure, preventing the accumulation of strain and undulations that would otherwise limit the total number of quantum wells to fewer than 32. By segmenting the structure, the patent enables fabrication of thicker stacks with higher device efficiency while maintaining manufacturing precision.
Solution Approach 2:
The patent introduces binary semiconductor layers as intermediary elements between the InP-based quantum well layers. These intermediary layers have matching lattice constants that reduce interfacial strain and prevent morphological defects. The binary layers serve as mediators that allow the coexistence of multiple InP quantum wells without defect formation, thereby resolving the contradiction between increasing quantum well numbers for improved efficiency and maintaining manufacturing precision.
2Productivity
If a thicker stack of quantum wells is fabricated to increase the number of active regions, then stimulated emission rate is improved, but morphological defects increase, limiting further thickness increase
Solution Approach 1:
The patent applies segmentation by inserting binary semiconductor layers at regular intervals within the quantum well stack. This segmentation enables the fabrication of thicker stacks with more active regions for enhanced stimulated emission, while the binary layers prevent morphological defects that would otherwise limit stack thickness. The segmentation approach removes the conventional limit of fewer than 32 InP-based layers.
Solution Approach 2:
The binary semiconductor layers serve as intermediary structures that enable increased stack thickness for higher productivity. These intermediaries maintain manufacturing precision throughout the thicker stack by preventing defect formation, thereby allowing the stimulated emission rate to be improved through increased numbers of active regions without being constrained by morphological defects.
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 growth of more quantum wells without defects, enhancing the efficiency of optoelectronic devices by increasing optical confinement and reducing scattering of light, leading to improved performance in PICs and other optoelectronic devices.
Implementation Method 1
The first layer is of a first semiconductor alloy comprising InP and the second layer is of a second semiconductor alloy comprising InP... A third layer comprising a binary semiconductor material having the first lattice constant is deposited in contact with the first stack... Each of the first and second semiconductor alloys comprises more than 8 layers and fewer than 16 layers, such that the total number of layers in the first stack is fewer than 32
Data Source
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AI summary
Examples relate to a method of fabricating a semiconductor structure with multiple quantum wells. The method comprises: providing a substrate comprising a binary semiconductor compound having a first lattice constant; depositing at least: a first layer on the substrate, the first layer of a first semiconductor alloy comprising InP, and a second layer in contact with the first layer, the second layer of a second semiconductor alloy comprising InP, to form a first stack of substantially planar semiconductor layers on the substrate; depositing in contact with the first stack a third layer of a binary semiconductor compound having the first lattice constant; depositing at least: a fourth layer on the third layer, the fourth layer comprising a third semiconductor alloy comprising InP, and a fifth layer in contact with the fourth layer, the fifth layer comprising a fourth semiconductor alloy comprising InP, to form a second stack of substantially planar semiconductor layers on the third layer.