Optical Semiconductor Device With Thin P-Type Layer To Reduce Leakage
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Solution Overview
Problem
Existing optical semiconductor devices with high resistivity semiconductor layers experience increased leak current and reduced optical output due to electron leakage from the active layer, especially at high current or high temperature operations.
Innovation Solution
A method of manufacturing optical semiconductor devices involves forming a mesa structure with an n-type cladding layer, an active layer, and a p-type cladding layer, where a thin p-type semiconductor layer with a specific thickness and impurity concentration is grown on the side faces and plane areas, and a current blocking semiconductor layer is used to bury the mesa structure, thereby reducing electron leakage and element capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high resistivity semiconductor layer is used to bury the mesa stripe, then element capacity is reduced and frequency band of direct modulation gets wider, but electron leakage from the active layer increases and leak current bypassing the active layer increases at high current or high temperature
Solution Approach 1:
A p-type semiconductor layer is introduced as an intermediary between the active layer and the high resistivity semiconductor layer. This intermediate layer acts as a barrier to electron leakage while maintaining the low capacitance benefits of the high resistivity layer. The p-type layer has a thickness of 5 nm to 45 nm and a specific impurity concentration that optimizes both leak current reduction and capacitance control.
Solution Approach 2:
The p-type semiconductor layer is selectively formed only in specific regions: on the side face of the mesa structure and on plane areas located at both sides of the mesa structure. This localized formation allows the layer to block electron leakage paths where they occur most frequently while minimizing the overall added capacitance. The product of thickness and impurity concentration is controlled to be 2.5×10^19 nm/cm³ or less in these specific regions.
2Productivity
If the active layer is buried with the high resistivity semiconductor layer, then element capacity is reduced, but optical outputting is restrained due to increased leak current
Solution Approach 1:
The p-type semiconductor layer serves as a mediator that preserves the low capacitance advantage of burying the active layer while preventing the harmful electron leakage. By positioning this layer between the active layer and the high resistivity semiconductor layer, the design maintains close spacing for low capacitance while the p-type layer's properties block electron transport to the high resistivity layer, thereby preserving optical output efficiency.
3Reliability
If a thin p-type semiconductor layer with specific thickness and impurity concentration is formed, then leak current is reduced and element capacity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies precise parameter ranges for the p-type semiconductor layer: thickness of 5 nm to 45 nm and a product of thickness and impurity concentration of 2.5×10^19 nm/cm³ or less. These parameter specifications define an optimal range that balances leak current reduction with manufacturing feasibility. The use of a thickness range rather than a single value provides manufacturing tolerance while maintaining effectiveness.
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 approach effectively reduces leak current and element capacity, enhancing optical output and modulation characteristics by ensuring the depletion layer covers the high resistivity semiconductor layer, thus improving the device's performance at high current and temperature conditions.
Implementation Method 1
ensuring the depletion layer covers the high resistivity semiconductor layer, thus improving the device's performance at high current and temperature conditions
Data Source
AI summary
A method of manufacturing an optical semiconductor device includes: forming a mesa structure having an n-type cladding layer, an active layer and a p-type cladding layer in this order on a substrate; forming a p-type semiconductor layer on a side face of the mesa structure and a plane area located at both sides of the mesa structure, the p-type semiconductor layer having a thickness of 5 nm to 45 nm on the plane area; and forming a current blocking semiconductor layer on the p-type semiconductor layer so as to bury the mesa structure, a product of the thickness of the p-type semiconductor layer and a concentration of p-type impurity of the p-type semiconductor layer on the plane area being 2.5×1019 nm/cm3 or less.