Indium films have been deposited at pressures less than 10−9 mm Hg and at higher pressures of specific residual gases. N2, H2, CH4, A, CO, and CO2 were found to have no measurable effect on the electrical or superconducting properties of these films when present in partial pressures of 10−5 mm Hg. For oxygen, a pronounced effect was observed when K (the ratio of oxygen molecules to indium atoms striking the substrate) exceeded 3%. The room temperature resistivity increased from 9.0 μohm-cm to 14 μohm-cm, the critical temperature decreased from (3.402±0.005)°K to (3.389±0.002)°K, the effective magnetic penetration depth increased from 630±100 A to over 1000 A. For 10−3<K<3×10−2, a larger apparent penetration depth was observed for films deposited through a mask due to edge effects. It was shown that indium films could be deposited at 100 A/sec on clean, baked substrates at 10−5 mm Hg with characteristics indistinguishable from those of films deposited in ultrahigh vacuum provided the partial pressures of oxygen and water vapor were below 10−7 and 10−5 mm Hg, respectively.

Caswell, H. L. (1961). Effect of Residual Gases on the Properties of Indium Films. Journal of Applied Physics, 32(12), 2641–2645.