Investigating the thermodynamics and kinetics of thin film reactions by differential scanning calorimetry

In this paper we demonstrate the utility of differential scanning calorimetry for investigating the thermodynamics and kinetics of a broad range of thin film reactions. We begin by describing differential scanning calorimeters and the preparation of thin film samples. We then cite a number of examples that illustrate how enthalpies of crystallization, heats of formation and enthalpies of interfaces can be measured using layered thin films of Ni/Al, Cu/Zr and Zr/Al and homogeneous thin films of Co–Si, Nb–Cu, Cr–Cu and Ge–Sn. Following these examples of thermodynamic measurements, we show how kinetic parameters of nucleation, growth and coarsening can also be determined from differential scanning calorimetry traces using layered thin films of Ni/Al, Ti/Al and Nb/Al and homogenous thin films of Co–Si and Ge–Sn. The thermodynamic and kinetic investigations highlighted in these examples demonstrate that one can characterize phase transformations that are relevant to commercial applications and scientific studies both of thin films and of bulk materials. Definitions of symbols β heating rate C heat capacity c,1c composition, composition change H,1H enthalpy, enthalpy change E activation energy g, g∗ geometrical factors for the interfacial enthalpy γH enthalpic part of the interfacial tension K heat transfer coefficient k rate constant k0 pre-exponential factor of the rate constant kB Boltzmann’s constant 3 multilayer period length m sample mass M molecular weight n Avrami exponent N nucleation site density nmole number of atoms in one molecule p grain growth exponent