J. Strube
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This thesis presents a complete study on the growth, fabrication, and characterization of Gallium Arsenide (GaAs) layers on Si(111) substrates using Metal-Organic Vapour Phase Epitaxy (MOVPE) for potential application in 3D Hall effect sensors. The (111) orientation was selected due to its compatibility with pyramid-shaped Hall sensor architectures and its reduced likelihood of antiphase domain formation compared to Si(100). GaAs is selected as the active material due to its high electron mobility and relatively small lattice mismatch with silicon, which together can enhance sensor sensitivity, signal to noise ratio and thermal stability.
A two-step growth approach was employed, consisting of a low temperature nucleation layer and a high temperature main layer. Systematic variation of temperature, V/III ratio, and growth rate revealed that smoother and more crystalline layers were obtained at higher growth rates and moderate precursor ratios. The optimal conditions produced continuous, well coalesced GaAs films with high crystalline quality at par with literature.
A major outcome of this work is the development of a complete, reproducible microfabrication flow for GaAs on Si devices. Enabling the fabrication of diodes, MOS capacitors, four-point probes and Hall structures, that allow for direct electrical characterisation of the grown layers.
Electrical performance was evaluated through micro-fabricated test structures, providing insights into carrier resistivity, contact resistance, carrier concentration and interface state density. While contact resistivity limited some analyses, the results demonstrate successful electrical integration of the grown material.
Future work will focus on refining the main layer growth conditions, optimising ohmic contacts, etching for GaAs and Si interfaces and completing Hall effect measurements under magnetic fields to fully assess the material’s sensing performance for Hall devices. ...
A two-step growth approach was employed, consisting of a low temperature nucleation layer and a high temperature main layer. Systematic variation of temperature, V/III ratio, and growth rate revealed that smoother and more crystalline layers were obtained at higher growth rates and moderate precursor ratios. The optimal conditions produced continuous, well coalesced GaAs films with high crystalline quality at par with literature.
A major outcome of this work is the development of a complete, reproducible microfabrication flow for GaAs on Si devices. Enabling the fabrication of diodes, MOS capacitors, four-point probes and Hall structures, that allow for direct electrical characterisation of the grown layers.
Electrical performance was evaluated through micro-fabricated test structures, providing insights into carrier resistivity, contact resistance, carrier concentration and interface state density. While contact resistivity limited some analyses, the results demonstrate successful electrical integration of the grown material.
Future work will focus on refining the main layer growth conditions, optimising ohmic contacts, etching for GaAs and Si interfaces and completing Hall effect measurements under magnetic fields to fully assess the material’s sensing performance for Hall devices. ...
This thesis presents a complete study on the growth, fabrication, and characterization of Gallium Arsenide (GaAs) layers on Si(111) substrates using Metal-Organic Vapour Phase Epitaxy (MOVPE) for potential application in 3D Hall effect sensors. The (111) orientation was selected due to its compatibility with pyramid-shaped Hall sensor architectures and its reduced likelihood of antiphase domain formation compared to Si(100). GaAs is selected as the active material due to its high electron mobility and relatively small lattice mismatch with silicon, which together can enhance sensor sensitivity, signal to noise ratio and thermal stability.
A two-step growth approach was employed, consisting of a low temperature nucleation layer and a high temperature main layer. Systematic variation of temperature, V/III ratio, and growth rate revealed that smoother and more crystalline layers were obtained at higher growth rates and moderate precursor ratios. The optimal conditions produced continuous, well coalesced GaAs films with high crystalline quality at par with literature.
A major outcome of this work is the development of a complete, reproducible microfabrication flow for GaAs on Si devices. Enabling the fabrication of diodes, MOS capacitors, four-point probes and Hall structures, that allow for direct electrical characterisation of the grown layers.
Electrical performance was evaluated through micro-fabricated test structures, providing insights into carrier resistivity, contact resistance, carrier concentration and interface state density. While contact resistivity limited some analyses, the results demonstrate successful electrical integration of the grown material.
Future work will focus on refining the main layer growth conditions, optimising ohmic contacts, etching for GaAs and Si interfaces and completing Hall effect measurements under magnetic fields to fully assess the material’s sensing performance for Hall devices.
A two-step growth approach was employed, consisting of a low temperature nucleation layer and a high temperature main layer. Systematic variation of temperature, V/III ratio, and growth rate revealed that smoother and more crystalline layers were obtained at higher growth rates and moderate precursor ratios. The optimal conditions produced continuous, well coalesced GaAs films with high crystalline quality at par with literature.
A major outcome of this work is the development of a complete, reproducible microfabrication flow for GaAs on Si devices. Enabling the fabrication of diodes, MOS capacitors, four-point probes and Hall structures, that allow for direct electrical characterisation of the grown layers.
Electrical performance was evaluated through micro-fabricated test structures, providing insights into carrier resistivity, contact resistance, carrier concentration and interface state density. While contact resistivity limited some analyses, the results demonstrate successful electrical integration of the grown material.
Future work will focus on refining the main layer growth conditions, optimising ohmic contacts, etching for GaAs and Si interfaces and completing Hall effect measurements under magnetic fields to fully assess the material’s sensing performance for Hall devices.