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

•Development of high quality p-type epitaxial GaAs on germanium (Ge).•P-type epitaxial GaAs on Ge substrate with surface roughness of ~0.8 nm.•Implementation of AlGaAs buffer layer and undoped-GaAs layer.•Integration of ALD Al2O3 gate dielectric with p-type epi-GaAs layer.

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 Al0.3Ga0.7As 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/Al0.3Ga0.7As/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.

Graphical abstractDevelopment 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 Al0.3Ga0.7As 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/Al0.3Ga0.7As/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. Figure optionsDownload full-size imageDownload as PowerPoint slide