Phase‐Control Enabled Superior Mechanical and Electrical Properties of Nanocrystalline Tungsten‐Molybdenum Thin Films

Abstract

The authors report on the design and stabilization of the mechanically hard and electrically resistive β‐phase W‐Mo nanocrystalline thin films at room‐temperature (RT). The W‐Mo films are deposited under different deposition temperatures in the range of Ts = RT–30 °C. Structural analyses indicate that, as deposited at RT, the W‐Mo films crystallize in the metastable β‐phase, while those deposited at higher Ts (100–300 °C) exhibit the thermodynamically stable α‐phase. The phase‐effect is significant on the mechanical characteristics; superior hardness (H); and modulus of elasticity (Er) are found in β‐than in α‐phase W‐Mo films. At the β‐to‐α phase transformation, significant reduction occurs in H (40 → 25 GPa) and Er (275 → 225 GPa) coupled with a reduction in electrical‐resistivity (320 → 180 µΩ‐cm). Their findings and the phase‐mechanical‐electrical property correlation established may provide further possibilities to design and tailor the performance of W‐based thin films for future electronic and electromechanical device applications.