Atomic layer deposited Al2O3 on high quality p-type epitaxial-GaAs/Ge for advanced III–V/Ge based device application

Highlights

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Development of high quality p-type epitaxial GaAs on germanium (Ge).

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P-type epitaxial GaAs on Ge substrate with surface roughness of ~0.8 nm.

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Implementation of AlGaAs buffer layer and undoped-GaAs layer.

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Integration of ALD Al₂O₃ gate dielectric with p-type epi-GaAs layer.

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Abstract

Development of high quality p-type epitaxial gallium–arsenide (epi-GaAs) on germanium (Ge) with sub-nm surface roughness is much sought after for the next generation high speed transistors application. High quality zinc doped p-type epitaxial GaAs with surface roughness of ~0.87 nm was grown on Ge substrates at 675 °C. Thin Al_0.3Ga_0.7As buffer layer and un-doped GaAs of 300 nm thick were introduced to suppress the Ge defects and auto-doping into epi-GaAs layer. The material and optical properties of the p-type epi-GaAs/un-doped GaAs/Al_0.3Ga_0.7As/Ge structures were examined through PL and Raman analysis. The metal–oxide–semiconductor capacitor (MOSC) was fabricated using p-type epi-GaAs layer and atomic-layer-deposited Al₂O₃ gate dielectric. The effective dielectric constant of the Au/Al₂O₃/p-epi-GaAs gate-stack is 5.9 and hysteresis voltage of 500 mV was observed. The epi-GaAs layer is p-type in nature with doping densities of 5×10¹⁷ cm⁻³.

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Graphical abstract

Development of high quality p-type epitaxial gallium–arsenide (epi-GaAs) on germanium with sub-nm surface roughness is much sought after for the next generation high speed transistors application. High quality zinc doped p-type epitaxial GaAs with surface roughness of ~0.87 nm was grown on Ge substrates at 675 °C. Thin Al_0.3Ga_0.7As buffer layer and un-doped GaAs of 300 nm thick were introduced to suppress the Ge defects and auto-doping into epi-GaAs layer. The material and optical properties of the p-type epi-GaAs/un-doped GaAs/Al_0.3Ga_0.7As/Ge structures were examined through PL and Raman analysis. The metal–oxide–semiconductor capacitor (MOSC) was fabricated using p-type epi-GaAs layer and atomic-layer-deposited Al₂O₃ gate dielectric. The effective dielectric constant of the Au/Al₂O₃/p-epi-GaAs gate-stack is 5.9 and hysteresis voltage of 500 mV was observed. The epi-GaAs layer is p-type in nature with doping densities of 5×10¹⁷ cm⁻³.

Keywords

• P-epitaxial-GaAs; 
• AlGaAs buffer layer; 
• ALD Al₂O₃; 
• GaAs/Ge integration
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• SOURCE:SCIENCEDIRECT
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