Charge profile in thin layers of Al2O3

The distribution of trapped electrons with respect to space and energy in thin layers of aluminum oxide of MAOS (metal-aluminumoxide-siliconoxide-silicon) capacitors was studied by photoionization. The oxide layers were charged from the n-type silicon by high field injection in the dark. Afterwards it was possible to release more than 85% of the trapped carriers using photons with energies up to 4.2 eV. The measurements of both the flatband voltages and the discharge currents of several bands of photon energies yielded two parameters for the determination of the spatial distribution for the trapped electrons in each energy interval.