Synthesis of borophane polymorphs through hydrogenation of borophene

Synthetic two-dimensional polymorphs of boron, or borophene, have attracted attention because of their anisotropic metallicity, correlated-electron phenomena, and diverse superlattice structures. Although borophene heterostructures have been realized, ordered chemical modification of borophene has not yet been reported. Here, we synthesize “borophane” polymorphs by hydrogenating borophene with atomic hydrogen in ultrahigh vacuum. Through atomic-scale imaging, spectroscopy, and first-principles calculations, the most prevalent borophane polymorph is shown to possess a combination of two-center–two-electron boron-hydrogen and three-center–two-electron boron-hydrogen-boron bonds. Borophane polymorphs are metallic with modified local work functions and can be reversibly returned to pristine borophene through thermal desorption of hydrogen. Hydrogenation also provides chemical passivation because borophane reduces oxidation rates by more than two orders of magnitude after ambient exposure.

Correlative analysis of embedded silicon interfaces passivation by “Kelvin probe force microscopy” and “corona oxide characterization of semiconductor”

We report a correlative analysis between corona oxide characterization of semiconductor (COCOS) and Kelvin probe force microscopy (KPFM) for the study of embedded silicon-oxide interfaces in the field of chemical and field-effect passivation. Analyzed parameters by these measurements are linked to different factors and specifically to defects density of embedded silicon-dielectric interfaces, surface band bending or the distribution of charges in the nearest surface volume. Furthermore, this COCOS-KPFM correlative analysis turns out to be a useful method to access to chemical and field-effect passivation. We confirm that it is possible to differentiate the influence of local band bending on sample passivation (i.e. field effect passivation) from the effects due to the local recombination rates (i.e. chemical passivation). The measurements were carried on five different passivation layers, precisely, 10.5 nm-thick SiO2, 50 nm-thick SiN, 7nm-thick Al2O3, 7 nm-thick HfO2 and double layer of 7 nm-thick Al2O3 below 53 nm-thick Ta2O5. This correlative analysis indicates that HfO2 present to be the best chemical passivation and SiN is the worst case in term of field effect passivation for p-type silicon. Additionally, we confirm that Ta2O5 layer on top of Al2O3 increase the defects density.

Оптические и электронные свойства пассивированных поверхностей InP(001)

The effect of chemical passivation in solutions of ammonium sulfide (NH4)2S on the optical and electronic properties of the n-InP (001) surface has been studied. It has been shown that treatment in a 4% aqueous solution of (NH4)2S leads to a decrease of surface band bending and localized charges in near-surface region in the 2 times. Processing in a 4% alcoholic solution of (NH4)2S leads to a decrease in these parameters in 3 times, and moreover, the barrier photovoltage and also reduces in three times.