Robust excitons dominate the optical properties of atomically thin semiconductors based on transition-metal dichalcogenides (TMDs) [1]. Nonetheless, a crucial question persists: What is the exciton formationmechanism, and how does this process occur in two-dimensional semiconductor materials ?This study addresses this fundamental problem through polarization-dependent micro-photoluminescence (PL)studies performed at cryogenic temperatures (4K) on hBN-encapsulated and charge-tunable TMD monolayersclose to the neutrality point. The results of our experiments performed on both WSe2 and MoS2 MLs clarifythe role played by the two potential formation mechanisms: a) geminate and b) bimolecular. The geminateexciton formation process corresponds to the monomolecular annihilation of the photogenerated correlatedelectron-hole pair. In contrast the non-geminate formation results from the random bimolecular binding of twofree charges, losing all correlation between the excitation photon and the electron-hole pair of the exciton.For excitation energies below the band gap, we show that the geminate mechanism prevails as expected.whereas above the band gap, both geminate and bimolecular process coexist [2]. This means that we must gobeyond the simple description used until now of either a totally geminate or totally bimolecular formationprocess.