We present p-p, p-pbar and pbar-pbar correlation functions constructed in Au+Au collisions at sqrt = 62 GeV and sqrt = 200 GeV by the STAR detector at RHIC. The large statistics available allow us to extract proton and anti-proton source size parameters with good accuracy. We account for the systematic errors due to residual correlations induced by Lambda and Sigma feeddown by introducing a new correction scheme. We compare our experimental results with theoretical predictions for different centralities and collision energies. We especially investigate whether or not the proton source size scales as predicted by flow with respect to the measured pion source size. Furthermore, the p-pbar correlation function allows us to check the validity of the expectation that protons and anti-protons are emitted on average at the same space-time position. The p-pbar correlation functions can also be used to measure the scattering lengths driving the p-pbar annihilation process. Thus, we are now able to gain new insights about the baryon production and interaction mechanisms thanks to the large statistics available in STAR and to the new residual correlation correction method that we have developed.