Semiconductor Optical Device AlInP Diffusion Barrier
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Solution Overview
Problem
Current semiconductor optical devices face limitations in reducing device resistance, which restricts modulation speed due to zinc (Zn) doping issues, leading to increased optical loss and lattice misfit dislocations when using AlGaInP materials.
Innovation Solution
Incorporating a thin AlInP layer with controlled Al concentration before forming a Mg doped InP layer, preventing doping delays and reducing lattice misfit, while maintaining low device resistance and minimizing bandgap effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Zn doping concentration is increased to reduce device resistance, then device resistance decreases, but Zn diffusion in MQW layer increases causing optical loss and deteriorating laser characteristics
Solution Approach 1:
An AlInP layer is introduced as an intermediary barrier between the p-type cladding layer and the MQW layer. This intermediate layer prevents Zn atoms from diffusing into the MQW layer while allowing the p-type cladding layer to maintain high doping concentration for low device resistance. The AlInP layer acts as a diffusion barrier that mediates the interaction between the doped cladding layer and the sensitive active layer.
Solution Approach 2:
The structure is segmented by dividing the p-type cladding layer into two distinct parts: an upper p-type cladding layer with high Zn doping concentration for low resistance, and a lower p-type cladding layer with lower Zn doping concentration to minimize diffusion. This segmentation allows each layer to optimize its doping concentration for its specific function without compromising the other.
2Object-generated harmful factors
If Al concentration in the first semiconductor layer is increased to prevent Zn diffusion, then Zn diffusion is reduced, but lattice misfit dislocation increases due to lattice constant difference
Solution Approach 1:
The Al concentration in the AlInP layer is precisely controlled within the range of 1×10^16 to 1×10^20 atoms/cm³. This parameter optimization ensures that the layer is sufficiently thick and concentrated to act as an effective Zn diffusion barrier, while simultaneously maintaining a low enough Al concentration to minimize lattice mismatch with the InP-based MQW layer, thereby reducing dislocation formation.
3Object-generated harmful factors
If Mg is used as dopant instead of Zn to reduce diffusion, then doping delay occurs in AlGaInP material
Solution Approach 1:
The patent changes the material composition from AlGaInP to InP for the cladding layers where Mg doping is applied. This parameter change (material composition) eliminates the doping delay issue associated with Mg in AlGaInP while maintaining the low diffusion characteristics of Mg, allowing effective use of Mg as a dopant without the time loss problem.
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 allows for reduced device resistance, improved modulation characteristics, and enhanced reliability with high optical output and yield rates, even in long-term operations.
Implementation Method 1
an AlInP layer with a controlled Al concentration is formed before forming a Mg doped InP layer
Implementation Method 2
a Mg doped InP layer, preventing doping delays and reducing lattice misfit
Data Source
AI summary
To provide a semiconductor optical device with device resistance reduced for optical communication. The semiconductor optical device includes an active layer (306) for emitting light through recombination of an electron and a hole; a diffraction grating (309) having a pitch defined in accordance with an output wavelength of the light emitted; a first semiconductor layer (311) including at least Al, made of In and group-V compound, and formed on the diffraction grating; and a second semiconductor layer (307) including Mg, made of In and group-V compound, and formed on the first semiconductor layer (311).