Germanium Layer Phosphorus Doping Lattice Integrity
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Solution Overview
Problem
Conventional doping techniques for semiconducting materials face limitations in achieving high concentrations of activated dopants due to lattice damage and dopant diffusion issues, particularly in advanced semiconductor fabrication processes, which restrict the performance of electronic and optoelectronic devices.
Innovation Solution
A two-step doping process involving in situ and ex situ methods, where phosphorus dopant atoms are incorporated into a germanium layer during growth and subsequently diffused through the layer to achieve a high concentration of activated dopants, enhancing diffusivity and minimizing lattice damage, thereby overcoming the limitations of conventional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature annealing is used to enhance dopant activation, then dopant activation is improved, but dopant diffusion increases causing dopant loss
Solution Approach 1:
The patent applies preliminary action by performing in situ doping during material growth to pre-establish dopant distribution before subsequent processing steps. This preliminary doping ensures that dopants are already positioned in the material lattice, reducing the need for high-temperature annealing that would cause diffusion and loss.
Solution Approach 2:
The patent changes the temperature parameter by avoiding high-temperature annealing processes. Instead, it uses lower temperature processing combined with in situ doping during growth, fundamentally altering the thermal regime to prevent dopant diffusion while still achieving adequate activation.
2Quantity of substance
If ion implantation is used to achieve high dopant concentration, then dopant concentration is improved, but lattice damage increases reducing activation
Solution Approach 1:
The patent uses in situ doping during material growth as a preliminary action that incorporates dopants directly into the growing crystal lattice without causing damage. This approach establishes high dopant concentration and proper lattice positioning simultaneously, eliminating the need for subsequent ion implantation that would cause lattice damage.
Solution Approach 2:
The patent introduces controlled defects or intermediate states during the doping process that facilitate dopant incorporation without creating severe lattice damage. These intermediates act as pathways for dopant integration that preserve lattice integrity while achieving high concentration.
3Reliability
If in situ doping is used during material growth, then lattice damage is minimized, but dopant concentration is limited by surface poisoning
Solution Approach 1:
The patent performs in situ doping as a preliminary action during material growth, establishing dopant distribution before surface poisoning can occur. By incorporating dopants during the growth phase rather than attempting to add them afterward, the system achieves both high concentration and lattice integrity.
Solution Approach 2:
The patent maintains continuous doping action throughout the material growth process, ensuring that dopants are continuously incorporated as the material forms. This continuous process prevents surface poisoning by keeping the surface active and avoiding the accumulation of poisoned surface states that would block further dopant incorporation.
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 attainment of high concentrations of activated dopants, enabling the production of high-performance optoelectronic devices, such as Ge lasers, that were previously unachievable with conventional methods, while preserving the integrity of the semiconductor material.
Implementation Method 1
a layer of germanium is formed having a germanium layer thickness, while in situ incorporating phosphorus dopant atoms at a concentration of at least about 5×1018 cm−3 through the thickness of the germanium layer during formation of the germanium layer
Implementation Method 2
Additional phosphorus dopant atoms are ex situ incorporated through the thickness of the germanium layer, after formation of the germanium layer
Data Source
AI summary
In a method for electrically doping a semiconducting material, a layer of germanium is formed having a germanium layer thickness, while in situ incorporating phosphorus dopant atoms at a concentration of at least about 5×1018 cm−3 through the thickness of the germanium layer during formation of the germanium layer. Additional phosphorus dopant atoms are ex situ incorporated through the thickness of the germanium layer, after formation of the germanium layer, to produce through the germanium layer thickness a total phosphorus dopant concentration of at least about 2×1019 cm−3.