Growth and structure of Ni films radio frequency sputter deposited on GaAs(001) covered with Ti film

A study is made of the growth mode of Ni films on the GaAs(001) substrates at 300 deg. C by rf magnetron sputtering. To restrain chemical reaction at the Ni/GaAs interface Ti films thinner than 700 nm are inserted into the interface. Thin film x-ray diffraction as well as normal x-ray diffraction, cross sectional transmission electron microscopy, and atomic force microscopy are used to characterize the structure of the Ni/Ti/GaAs(001) system. Electrical properties are studied by measuring resistivity and its temperature coefficient at temperature lower than 300 K. Growth structure of Ti films depends on substrate temperature. The 00·1-textured growth without compound formation is completed optimally at 300 deg. C. The films consist of columnar grains 100-200 nm in diameter. The columnar growth of the Ti film is perfectly succeeded by the Ni film with the growth mode of Ni(111)//Ti(00·1)//GaAs(001) and Ti(11·0)//GaAs(110) where Ni(001) is nearly parallel to GaAs(111). No solid reaction between Ni, Ti, and GaAs is detected. Without the Ti interlayer the Ni film is depleted by formation of the compound NiAs2, resulting in an abrupt decrease of temperature coefficient of resistivity. In conclusion, it is confirmed that the crystallographically well orientated Ni film can grow on the GaAs(001) through the Ti interlayer without any compound formation at the interfaces