  Single-layer quantum dot gate potential causes type-II band alignment, i.e.
electrostatically confines holes and repels electrons, or vice versa. Hence,
the confinement of excitons in gated type II quantum dots involves a delicate
balance of the repulsion of electrons due to the gate potential with the
attraction caused by the Coulomb interaction with a hole localized in the
quantum dot. This work presents a theory for neutral excitonic complexes within
gated $\text{WSe}_\text{2}$ quantum dots, considering spin, valley, electronic
orbitals, and many-body interactions. We analyze how the electron-hole
attraction depends on a range of system parameters, such as screened Coulomb
interaction, strength of confinement of holes, and repulsion of electrons.
Using an atomistic tight binding model we compute valence and conduction band
states within a computational box comprising over one million atoms with
applied gate potential. The atomistic wavefunctions are then used to calculate
direct and exchange Coulomb matrix elements for a fictitious type I quantum
dot, and to obtain a spectrum of interacting electron-hole pairs. Next, we
study the effect of repulsive potential, pulling away electrons from the
valence hole. We determine whether electron-hole pairs are sufficiently
attracted to overcome electron repulsion by the confinement potential. Finally,
we compute the dipole transition between hole and electron states to obtain the
absorption spectrum.
