Provided are a Ge precursor for low temperature deposition containing Ge, N, and Si, a GST thin layer doped with N and Si formed using the same, a memory device including the GST thin layer doped with N and Si, and a method of manufacturing the GST thin layer. The cover bodies 30 and 70 are construed so as to be movable between a first position for covering the wall surface provided with said utility mechanism, and a second position for opening the wall surface. In yet another aspect, improved procedures for installing permanent, implant-supported dental restorations are disclosed, including an immediate loading procedure.