Semi-insulating InP Buried Layer for Optical Feedback Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical semiconductor devices face issues with reflection at exit end surfaces, leading to unstable operation and increased parasitic capacitance, which restricts high-speed operation and design flexibility, and the formation of eaves by buried layers can complicate production and optical beam injection.
Innovation Solution
A semi-insulating buried semiconductor layer is formed using an MOCVD process with organic chlorine-containing substances, creating a flat top surface and sloped regions to suppress eaves formation and allow for non-restricted mesa stripe direction, while maintaining a consistent layer thickness to reduce optical feedback and parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If p/n carrier blocking layers are used to suppress reflection at the exit end surface, then reflection suppression is improved, but parasitic capacitance increases which degrades high-speed operation
Solution Approach 1:
The invention changes the material parameter from conventional p/n carrier blocking layers to semi-insulating InP buried layer, fundamentally altering the electrical properties to achieve low capacitance while maintaining reflection suppression functionality
Solution Approach 2:
The semi-insulating InP buried layer is selectively positioned at the lateral sides of the mesa stripe, providing localized reflection suppression without the capacitive penalty of extended p/n blocking structures
2Manufacturing precision
If mesa stripe extension direction is restricted to [011] directions to prevent eaves formation, then manufacturing precision is improved, but design flexibility and productivity are degraded
Solution Approach 1:
The invention changes the crystal orientation parameter by forming the semi-insulating InP buried layer on the (311)B surface, which fundamentally alters the growth characteristics to prevent eaves formation regardless of mesa stripe orientation
Solution Approach 2:
The (311)B surface buried layer structure provides universal eaves prevention that works for any mesa stripe extension direction, making the process universally applicable and eliminating the need for precise directional control
3Area of stationary object
If buried layers grow to form eaves on the mesa stripe, then coverage is improved, but optical beam injection becomes difficult and production is complicated
Solution Approach 1:
The invention uses the curved (311)B surface geometry to control buried layer growth, creating a rounded profile that naturally prevents eave formation while maintaining adequate coverage, facilitating smooth optical beam injection
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 solution effectively suppresses eaves formation, allows for flexible mesa stripe direction, reduces optical feedback, and enhances high-speed operation by minimizing parasitic capacitance, thereby stabilizing optical communication systems and improving production efficiency.
Implementation Method 1
a semi-insulating buried semiconductor layer formed on said semiconductor substrate so as to cover said first and second regions continuously... said step of depositing said semi-insulating buried semiconductor layer being conducted by adding an organic chlorine-containing substance
Implementation Method 2
said mesa stripe waveguide amplifying light guided therethrough by stimulated emission
Implementation Method 3
there are formed flat regions in said first region along said mesa stripe waveguide respectively at said right and left regions of said mesa stripe waveguide with a flat surface at a level coincident to a top surface of said mesa stripe waveguide, and such that there are formed first and second sloped regions
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3D
AI summary
An optical semiconductor, includes a semiconductor substrate (41) having a (100) principal surface, a waveguide mesa stripe (M1) formed on a first region (L1) of the semiconductor substrate, the waveguide mesa stripe guiding a light therethrough; a plurality of dummy mesa patterns (M2,M3) formed on the semiconductor substrate (41) in a second region (L2) at a forward side of the first region, and a semi-insulating buried semiconductor layer (50) formed on the semiconductor substrate (41) so as to cover the first and second regions (L1,L2) continuously, the semi-insulating buried semiconductor layer (50) filling a right side and a left side of the waveguide mesa stripe in the first region (L1) and a gap between the plurality of dummy mesa patterns (M4,M3) in the second region (L2). This structure decreases the sensitivity against optical feedback from externally reflected light in the case of the device being a laser diode.