The PHENIX experiment at RHIC measured single electron spectra in p+p, d+Au and Au+Au collisions at√SNN= 200 GeV, and in Au+Au collisions at√SNN=62.4 GeV. In these spectra, electrons from semi-leptonic decays of charmed particles are the dominant contribution after subtraction of all ’photonic’ sources (photon conversions, Dalitz decays, decays of light vector mesons). The p+p open charm production cross-section is found to be in good agreement with pQCD NLO calculations. The shape of the distributions obtained for p+p interactions is compared with those observed for nucleus-nucleus collisions.From p+p to d+Au and Au+Au interactions, open charm production is found to scale with the number of binary collisionsN_coll. Au+Au data at √SNN=62.4 GeV is compatible with the ISR p+p results scaled byN_coll. The elliptic flow parameter v₂of heavy flavor electrons has also been measured, and is found to be non-zero in the intermediate PT range.