Buried Semiconductor Optical Device Modulation Bandwidth
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Solution Overview
Problem
The integration of a buried semiconductor optical device with an Electro-Absorption (EA) modulator faces issues with parasitic capacitance and foreign body formation due to the use of ruthenium doping, which affects the modulation bandwidth and cleavage quality.
Innovation Solution
A buried semiconductor optical device is designed with a layered structure comprising semi-insulating InP sublayers and additional sublayers of InGaAs, InAlAs, InGaAlAs, InGaAsP, or InAlAsP, where the second sublayer reacts with In to suppress foreign body formation and reduce parasitic capacitance, and the third sublayer is doped with Ru to enhance modulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ruthenium doping is added to the buried semiconductor layer to improve fast response, then modulation bandwidth is improved, but the number of foreign bodies increases
Solution Approach 1:
The buried layer is segmented into multiple sublayers: a first sublayer containing Ru dopant for fast response, and a second sublayer free of foreign bodies for high-quality cleavage. This segmentation allows each sublayer to fulfill its specific function without compromising the other, resolving the contradiction between modulation bandwidth and foreign body formation.
Solution Approach 2:
Different regions of the buried layer are assigned different compositions and properties. The first sublayer has Ru doping for electrical performance, while the second sublayer has optimized composition for mechanical performance. This local differentiation allows simultaneous achievement of fast response and clean cleavage surfaces.
2Speed
If the thickness of the buried layer is increased to reduce parasitic capacitance, then modulation bandwidth is improved, but foreign body formation increases
Solution Approach 1:
The thick buried layer is divided into functional segments: the first sublayer provides the necessary thickness for low parasitic capacitance and contains Ru for fast response, while the second sublayer maintains the overall thickness for electrical performance but excludes foreign bodies through optimized deposition conditions.
Solution Approach 2:
The second sublayer acts as an intermediary between the Ru-doped first sublayer and the overlying active structures. It provides a clean interface that prevents foreign body propagation while maintaining the electrical benefits of the thick Ru-doped region.
3Object-generated harmful factors
If low temperature deposition is used to reduce In migration, then foreign body formation is reduced, but modulation bandwidth may be affected
Solution Approach 1:
The deposition parameters are optimized to achieve low temperature growth that suppresses In migration and foreign body formation, while the Ru doping concentration and layer thickness are adjusted to compensate for any potential reduction in modulation bandwidth, achieving both goals simultaneously.
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 reduces the number of foreign bodies and improves the modulation bandwidth, enabling more efficient light confinement and cleavage quality, thus enhancing the performance and yield of the semiconductor optical device.
Implementation Method 1
the second sublayer reacts with In to suppress foreign body formation and reduce parasitic capacitance
Implementation Method 2
the buried semiconductor layer doped with Ru suppresses diffusion of dopants like zinc (Zn) in a p-type cladding layer of the EA modulator into the buried semiconductor layer
Implementation Method 3
The low temperature deposition reduces migration of In over the surface of the substrate
Implementation Method 4
An Electro-Absorption (EA) Modulator is used for modulating a continuous wave light emitted from an oscillator
Data Source
AI summary
A buried semiconductor optical device comprises a semiconductor substrate; a mesa-stripe portion including a multi-quantum well layer on the semiconductor substrate; a buried layer consisting of a first portion and a second portion, the first portion covering one side of the mesa-stripe portion, the second portion covering the other side of the mesa-stripe portion, and the first portion and the second portion covering a surface of the semiconductor substrate; and an electrode configured to cause an electric current to flow through the mesa-stripe portion, the buried layer comprising, from the surface, a first, second, and third sublayer, the first and third sublayer each consisting of semi-insulating InP, the first sublayer and the second sublayer forming a pair structure, the second sublayer being located above the multi-quantum well layer, and the second sublayer consisting of one or more layers selected from InGaAs, InAlAs, InGaAlAs, InGaAsP, and InAlAsP.