Present work reports the results of activities intended to reach thin Si(Li) detector entrance window on the diffusive lithium layer side. It was established that the new n-contact represented by a heterostructure of unalloyed amorphous n-type silicon a-Si:H allows one to achieve the entrance window thickness 3-4 orders of magnitude smaller than the lithium-side entrance window of standard Si(Li) detectors. The films of amorphous silicon were synthesized with MASD (magnetron assisted silane decomposition) method in mixture of SiH₄ (25%) and Ar (75%) gases. Lithium layer surface resistivity and silicon target type (n-or p-) affection on electrical properties of Si(Li) detector contact produced were studied. The investigation performed had led to a technology of Si(Li) detector production with thickness of the entrance window on the diffusive lithium layer side below 0.1 μm.