Hydrogen-Multivalent Acceptor Complexes in High-Purity Germanium

Using copper (a fast diffusing, multivalent acceptor impurity in Ge) we have shown that hydrogen can form complexes with multivalent acceptors. Hydrogen is incorporated in the Ge single crystal during its growth from a melt in a H2 atmosphere. By analogy with the interaction between lithium and multivalent acceptors we find two acceptor like complexes: Cu-H and Cu-H2. Using Photothermal Ionization Spectroscopy and Hall effect we assign the following energy levels: Cu-H: EV + 17.5 meV and EV + 170 ± 20 meV and Cu-H2: EV + 17.0 meV. According to our model the Cu-H3 complex is neutral. Consequences for the performance of large volume radiation detectors are discussed.