Effect of varying plasma properties on III-nitride film growth by plasma enhanced atomic layer epitaxy

Plasma enhanced atomic layer epitaxy (PEALE) is a layer-by-layer crystalline growth technique that is based on a pair of self-terminating and self-limiting gas-surface half-reactions, in which at least one half-reaction involves species from a plasma. The inclusion of plasma generally offers the benefit of substantially reduced growth temperatures and greater flexibility in tailoring the gas-phase chemistry to produce varying film characteristics. The benefits plasmas provide come at the cost of a complex array of process variables that often challenge the ability to predict, a priori, the influence of any one input parameter. This work focuses on the use of plasma diagnostics to inform the choice of process conditions for PEALE. Optical emission spectroscopy in the plasma source and charged particle collectors at the substrate are employed to characterize a Fiji 200 (Veeco) deposition tool. In particular, the authors assess the total ion flux reaching the substrate surface and the relative fractions of atomic and molecular species generated in the plasma source under a variety of gas input flow fractions (Ar/N-2 and Ar/N-2/H-2) used in the PEALE growth of AlN and InN films. Changes in plasma parameters are then linked with changes in film characteristics.