B.; Yakovkin, I. N.; and Dowben, Peter A., "Effect of gadolinium doping on the electronic band structure of europium oxide" (2012 [111]. Angular-resolved photoemission spectroscopy reveals electron pockets around the X points in Gd-doped EuO, indicating that the band gap in EuO is indirect. Combined photoemission and inverse photoemission measurements show an apparent transition from n-type to p-type behavior, which is likely due to band bending near the polar (111) surface.

Gd 2 O 3 and Gd-doped HfO 2 films were deposited on p-type silicon substrates in a reducing atmosphere. Gd 4f photoexcitation peaks at roughly 7 and 5 eV below the valence band maximum have been identified using the resonant photoemission of Gd 2 O 3 and Gd-doped HfO 2 films, respectively. In the case of Gd 2 O 3 , strong hybridization with the O 2p band is demonstrated, and there is evidence that the Gd 4f weighted band exhibits dispersion in the bulk band structure. The rectifying (diode-like) properties of Gd-doped HfO 2 -silicon and Gd 2 O 3 -silicon heterojunctions are demonstrated.

Highly doped or alloyed Gd2O3 in HfO2 films form heterojunction diodes with silicon. Single neutron capture events can be identified with a Hf0.85Gd0.15O1.93 to n-type silicon heterojunction. With long pulse integration times and suppression of the smaller pulses, there is agreement between the key pulse height spectral features and those predicted by Monte Carlo simulations. The latter align very well with the decay channels of the Gd following neutron capture, particularly those involving the Gd K-shell Auger electron resonances.

Molecular films of quinonoid zwitterions, of the general formula C 6 H 2 (/O) 2 (/NHR) 2 , have been shown to display electronic properties highly dependent on the nature of the N-substituent R when deposited on gold substrates. The different spacing and organization of the molecules can lead to molecular films with semi-metal or dielectric behavior. With the long term goal to establish how packing effects in the solid state correlate with properties as thin films, we first attempted to identify by X-ray diffraction analysis candidate molecules showing suitable packing arrangements in the crystalline state. To this end, we have prepared a series of new functionalized, enantiopure or sterically-hindered quinonoid zwitterions and established the crystal structure of those with R ¼ CH 2 -CH 2 -Ph (6), CH 2 -CH 2 -CH 2 -Ph (7), CH 2 -CH 2 -C 6 H 4 ) (15), CH 2 -((4-NH 2 )-C 6 H 4 ) (19) and CH 2 -CH 2 -((3,4-(OCH 3 ) 2 )-C 6 H 3 ) (24). An analysis of the crystal packing of three molecules, 5, 13 and 15, selected as illustrative examples for comparisons, was carried out and it was unexpectedly found that these chemically very similar molecules gave rise to different packing in the bulk, with resulting thin films showing different electronic properties. Various methods have been used for the characterization of the films, such as synchrotron radiation-based FTIR spatial spectra-microscopy, which provided an anchoring map of zwitterion 15 on a patterned substrate (Au/SiO 2 ) showing its selective anchoring on gold. This is one of the best examples of preferential anchoring of a zwitterion and the sole example of spatial localization for a quinonoid zwitterion thin film.We have also used combined photoemission and inverse photoemission spectra and the data were compared to occupied and unoccupied DFT density state calculations.