High-energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) create hot, equilibrated matter that is commonly understood as a Quark-Gluon Plasma (QGP). The QGP is opaque to hard-scattered light quarks. This can be understood as a consequence of energy loss from gluon bremsstrahlung and tells us about the microscopic properties of the QGP. Heavy quarks (c, b) are expected to lose significantly less energy through radiation depending on their mass. Nevertheless, at high transverse momentum, where b production is expected to be significant, the energy loss of electrons from semi-leptonic heavy quark decays was found to be similar to that of light quarks. The PHENIX experiment has build and operated a silicon micro-vertexing detector with the express purpose of separating electrons from charm and bottom decays in order to shed light on the mechanisms of energy loss in the QGP. We will report on first results of charm and bottom production in Au+Au collisions at a center-of-mass energy of 200 GeV per nucleon-pair and their implications for the nature of the QGP.