Cross sections for electron scattering from atomic gallium*

The relativistic convergent close-coupling method is applied to calculate cross sections for electron scattering on atomic gallium.

Gallium is an important element for high-performance semiconductors such as gallium nitride and gallium oxide. Recent research into processes for effective growth of such semiconductors has tended towards methods using gas and plasma phase reactants, for finer growth control.

Due to gallium's thermal properties, it has also been proposed for use as a liquid plasma-facing surface in future fusion reactor chambers. Such a plasma-facing surface would inevitably interact with the plasma itself, which must be accounted for during reactor design.

The gallium atom is modelled as a quasi one-electron atom with an inert zinc-like Dirac-Fock core.

The integrated and momentum-transfer cross sections for elastic scattering are presented from the 4P$_{1/2,3/2}$ electronic states for incident energies between 0.03 eV and 1000 eV.

Integrated excitation cross sections are also presented from these initial states to the $4[d,f]$, $5[s,p,d]$, $6[s,p]$ and $7s$ manifolds, as well as cross sections for excitation of the 4P$_{1/2}$ state to the 4P$_{3/2}$ state.

Estimates were presented for the total single ionisation cross section and total cross section for scattering on gallium in the 4P$_{1/2,3/2}$ states, including direct ionisation from the $4p$, $4s$ and $3d$ electrons, and excitation-autoionisation contributions from $4s$ and $3d$ electrons.

The estimated ionisation cross section agrees well with existing experimental data.