Atomic Layer Deposited Molybdenum Nitride Thin Film: A Promising Anode Material for Li Ion Batteries

Molybdenum nitride (MoN_<i>x</i>) thin films are deposited by atomic layer deposition (ALD) using molybdenum hexacarbonyl [Mo­(CO)₆] and ammonia [NH₃] at varied temperatures. A relatively narrow ALD temperature window is observed. <i>In situ</i> quartz crystal microbalance (QCM) measurements reveal the self-limiting growth nature of the deposition that is further verified with <i>ex situ</i> spectroscopic ellipsometry and X-ray reflectivity (XRR) measurements. A saturated growth rate of 2 Å/cycle at 170 °C is obtained. The deposition chemistry is studied by the <i>in situ</i> Fourier transform infrared spectroscopy (FTIR) that investigates the surface bound reactions during each half cycle. As deposited films are amorphous as observed from X-ray diffraction (XRD) and transmission electron microscopy electron diffraction (TEM ED) studies, which get converted to hexagonal-MoN upon annealing at 400 °C under NH₃ atmosphere. As grown thin films are found to have notable potential as a carbon and binder free anode material in a Li ion battery. Under half-cell configuration, a stable discharge capacity of 700 mAh g⁻¹ was achieved after 100 charge–discharge cycles, at a current density of 100 μA cm<sup>–2