We used the low-energy μSR technique (LE-μSR) to extend our previous studies on the energy dependence of muonium (Mu) states in Si and insulators [T. Prokscha, E. Morenzoni, D.G. Eshchenko, N. Garifianov, H. Glückler, R. Khasanov, H. Luetkens, A. Suter, Phys. Rev. Lett. 98 (2007) 227401] to investigations on an undoped 0.15-mm-thick Ge (100) crystal. The Mu formation in the near-surface region from about 10 to 150 nm is probed with mean implantation energies between 2.5 and 17.4 keV. In this energy range the number of track electron-hole pairs varies as a function of energy between a few hundred and several thousand [R.C. Alig, S. Bloom, Phys. Rev. Lett. 35 (1975) 1522]. Similar behavior as in Si is observed between 30 and 150 K, i.e., a doubling of the diamagnetic fraction F_D (Mu⁺ or Mu^-) on lowering the energy E from 17.4 to 2.5 keV, corresponding to mean implantation depths of 130 and 17 nm, respectively. The fraction of Mu at the tetrahedral interstitial site (Mu_T) does not show a pronounced energy dependence. The change of F_D therefore can be attributed to a corresponding change of the bond-center Mu (Mu_BC) formation probability. This demonstrates that also in Ge the formation of Mu_BC clearly depends on the availability of excess charge carriers which the muon creates during the stopping process. Surprisingly, below 50K F_D starts to increase again for E>4 keV. Additionally, bulk μSR studies on a piece cut from the same sample shows the opposite trend in F_D below 50K, and distinct final charge states. More investigations are necessary to clarify this difference.