TiNi/GaAs Thin Film Structures for Gate Metallizations
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TiNi/GaAs Thin Film Structures for Gate Metallizations Chichang Zhang and Aris Christou Dept. Materials Science and Engineering, Univ. of Maryland at College Park College Park, Maryland, 20742 USA ABSTRACT Shape memory alloy TiNi thin films on GaAs have been investigated. A series of TiNi compositions were electron beam deposited on GaAs initially as thin multilayers of Ti and Ni. The intermetallic phase of TiNi was formed by annealing and complete intermixing of the multilayers at 370oC. The intermetallic phases were investigated with X-ray diffraction techniques. The annealing kinetics and resistivity investigations were carried out in order to minimize the sheet resistance of the intermetallic phase. TiNi Schottky barriers on GaAs have been fabricated and their performance will be reported. Additional investigations on surface morphology using the energy dispersive spectroscopy as well as TEM investigations show the correlation between microstructure, intermetallic phase formation and sheet resistance. INTRODUCTION TiNi alloy has been investigated for a long period partly because of its good electrical and mechanical properties, long fatigue life and high corrosion resistance. Even now people still take time in investigating its properties [1]. Today most endeavors are focused on its temperature dependent martensitic transformation and shape memory effect, which is mainly focused on its mechanical properties as well as its crystal structure [2] and phase transformation [3-5]. With the fast development of modern technology, various metals have been used in integrated circuits, including Al, Nb [6], as a gate metal in order to improve the performance of chips. In this paper we begin to use TiNi on GaAs for gate metallization and investigate its properties for the possibility of using TiNi alloy in the GaAs industry in the future. However, here we focus mainly on its electrical properties. EXPERIMENTAL DETAILS The sources (pure Titanium and Nickel) used in this work were received from Alfa Aesar Company. TiNi interweaving multilayers were deposited on GaAs (100) substrate by electron beam deposition under vacuum (
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