Researchers from the University of New Mexico, the University of Science and Technology of China, and the Max Planck Institute for Biophysical Chemistry have published a study that sheds light on the fundamental processes involved in chemical bond formation at semiconductor surfaces. The team, led by Bin Jiang and Hua Guo, has used advanced computational techniques to simulate the interaction of hydrogen atoms with a germanium surface, providing insights that could have practical applications in the energy sector, particularly in semiconductor manufacturing and hydrogen storage technologies.
The researchers employed a sophisticated simulation method that combines real-time, time-dependent density functional theory with Ehrenfest dynamics. This approach allowed them to reproduce experimental observations of hydrogen atom scattering from a germanium surface, specifically the bimodal translational energy loss and angular distributions. The simulations revealed a site-selective mechanism of electronically nonadiabatic energy transfer associated with the formation of different germanium-hydrogen (Ge-H) bonds.
When a hydrogen atom approaches a specific site on the germanium surface known as a rest-atom, it is strongly accelerated towards the potential minimum, forming a transient Ge-H bond. This bond formation triggers an ultrafast electron transfer event from the rest-atom to an adjacent germanium adatom, involving several crossings between the valence and conduction bands of the substrate. The rapid nature of this process means that electronic equilibration is not possible, leading to a conversion of the hydrogen atom’s kinetic energy into inter-band electronic excitation of the substrate. This mechanism is distinct from previously identified nonadiabatic energy transfer mechanisms at metal surfaces, which are mediated by electronic friction or transient negative ions.
In contrast, hydrogen atom collisions at other sites on the germanium surface also form a transient bond but exhibit no electronic excitation, resulting in less efficient energy loss in scattered hydrogen atoms. The nuclear-to-electronic energy transfer observed in this system reflects the electronic dynamics of covalent bond formation at a semiconductor surface.
The findings of this study, published in the journal Nature Communications, provide a deeper understanding of the fundamental processes involved in chemical bond formation at semiconductor surfaces. This knowledge could have practical applications in the energy sector, particularly in the development of more efficient semiconductor manufacturing processes and hydrogen storage technologies. By elucidating the mechanisms of energy transfer during chemical bond formation, researchers can potentially design materials and processes that optimize energy efficiency and performance.
In summary, the research highlights the importance of understanding the electronic dynamics of chemical bond formation at semiconductor surfaces. The insights gained from this study could contribute to the development of more advanced and efficient energy technologies, ultimately benefiting the energy industry and society as a whole.
This article is based on research available at arXiv.