Electron Band Alignment at Interfaces of Semiconductors with Insulating Oxides: An Internal Photoemission Study
Figure 16
Semilogarithmic plot of the photocurrent yield spectra of (100)Ge/a-Al2O3(10 nm)/Au capacitors fabricated using different alumina deposition methods as measured under (a) positive and (b) negative bias of 2 Volt applied to the top metal electrode. The inset in panel (a) illustrates determination of the electron IPE spectral thresholds using plots. The threshold energies are indicated for electron transitions from the VB of germanium into the CB of a-Al2O3 and into the CB of GeOx IL formed during oxide deposition. The vertical arrows and in panel (a) mark the energies of direct optical transitions in the Ge crystal. In panel (b) the vertical arrows mark the onsets of the photoconductivity in a-Al2O3 film and GeOx IL.
