Interdiffusion in Al/Ge sandwich structures

• Published in: Thin solid films 1978-09, Vol.53 (2), p.L5-L7
• Main Author: MgBenu, E.N.
• Format: Article
• Language: English
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(78)90023-8

Proc. Fifth Int. Conf. Metallurgical Coatings, San Francisco, Apr. 1978. See Met. A., 7910-72 0305. A Ge film was electron gun evaporated onto an Al film substrate kept at room temp. or 200 deg C. Evaporation rate was 10A sec-1 and final thickness 1000 A. A top film was evaporated onto the Ge, Al film thicknesses being approx =1000 A. Measurements of d.c. I/V characteristics were made on samples at room temp. soon after fabrication and after ageing for a year. Ge evaporated at room temp. was amorphous and that deposited at 200 deg C was crystalline. For fresh amorphous film resistivity was approx =2.5 x 104 Omega cm, attributed to large O content. Transport mechanism was a hopping process activation energy < =0.1-0.2 eV. Resistivity dropped at elevated temp. Increased conductivity was expected for crystalline material compared with amorphous material. For aged film conductivity increased by about one order of magnitude in all films compared with when they were fresh. This was attributed to interdiffusion between Al and Ge at room temp., the Al diffusing along Ge grain boundaries. Metal crystals saturated either the amorphous or crystalline Ge matrix and appeared to dominate the 10 ref.--E.J.S.