Evidence of hydrogen modulation in amorphous germanium prepared by reactive evaporation

Reactive evaporation of germanium under a flow of hydrogen atoms on substrates maintained at liquid‐nitrogen temperature allows us to obtain a‐Ge:H thin films and multilayers. The material contains a considerable amount of polygermane bonds and is porous, as shown by low angle x‐ray scattering performed on Ge/Ge:H/... multilayers. The stability of hydrogen is measured by resistivity measurements and by effusion experiments. Finally, low angle neutron scattering shows that it is possible to modulate hydrogen in Ge/Ge:H/Ge/Ge:D/... multilayers with 40 A thick layers.