Lu Hongliang

Characterization of Al2O3 Thin Films on GaAs Substrate Grown by Atomic Layer Deposition

Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300°C. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and x-ray photoelectron spectroscopy (XPS). The XRD results show that the as-deposited Al2O3 film is amorphous. For 30 atomic layer deposition growth cycles, the thicknesses of the Al2O3 thin film and the interface layer from the HRTEM are 3.3 nm and 0.5 nm, respectively. XPS analyses reveal that the Al2O3/GaAs interface is almost free from As2O3.

Effect of Trimethyl Aluminium Surface Pretreatment on Atomic Layer Deposition Al2O3 Ultra-Thin Film on Si Substrate

Ultra-thin Al2O3 dielectric films have been deposited on Si substrates by using trimethyl aluminium (TMA) and water as precursors in an atomic layer deposition (ALD) system. Growth of the interfacial layer between ultra-thin Al2O3 and the Si substrate is effectively suppressed by a long-time TMA surface pretreatment of the Si substrate prior to Al2O3 atomic layer deposition. High resolution transmission electron microscopy (TEM) images show that the thickness of the interfacial layer is reduced to be 0.5 nm for the sample with TMA pretreatment lasting 3600 s. The x-ray photoelectron spectroscopy results indicate that the Al2O3 film deposited on the TMA-pretreated Si surface exhibits very good thermal stability. However, a hysteresis of about 50 mV is observed in the C–V curve of the samples with the TMA pretreatment.