Bruce C. C. Cowie

Looking 100 Å deep into spatially inhomogeneous dilute systems with hard x-ray photoemission

We present hard x-ray photoemission measurements from GaAs samples with a 10-A-thick layer of AlAs buried at different depths. The intensity trend versus kinetic energy of the Al 1s signal allows extraction of the x-ray attenuation length, which we find to reach ∼100A at a kinetic energy of 6 keV. On one sample exposed to air for several days we obtain qualitative information on the oxidation at different depth scales by exploiting the energy dependence of the attenuation length. This suggests the strong potential of hard x-ray photoemission in the nondestructive characterization of diluted materials on a depth scale interesting to modern nanotechnologies.

Nondestructive diagnostics of high-κ dielectrics for advanced electronic devices

The authors present novel results on the interface between silicon and the high-κ oxides Al2O3 and HfO2 grown by atomic layer deposition. The determination of the thickness of the interfacial layer between oxide and Si(100) is crucial to the evaluation of the performances of devices based on high-κ dielectrics. They find through hard x-ray photoemission spectroscopy (HaXPES) that no interfacial layer forms between Al2O3 and Si(100) whereas almost one monolayer forms between HfO2 and Si(100). HaXPES does not involve any destructive procedure nor any sample preparation. High-energy photoemission could therefore be widely employed for the characterization of real devices.