Nanostructured light-absorbing crystalline CuIn(1-x)GaxSe2 thin films grown through high flux, low energy ion irradiation

作者：Hall Allen J^*; Hebert Damon; Shah Amish B; Bettge Martin; Rockett Angus A

来源：Journal of Applied Physics, 2013, 114(15): 153505.

DOI：10.1063/1.4823987

A hybrid effusion/sputtering vacuum system was modified with an inductively coupled plasma (ICP) coil enabling ion assisted physical vapor deposition of CuIn1-xGaxSe2 thin films on GaAs single crystals and stainless steel foils. With <80W rf power to the ICP coil at 620-740 degrees C, film morphologies were unchanged compared to those grown without the ICP. At low temperature (600-670 degrees C) and high rf power (80-400 W), a light absorbing nanostructured highly anisotropic platelet morphology was produced with surface planes dominated by {112}(T) facets. At 80-400W rf power and 640-740 degrees C, both interconnected void and small platelet morphologies were observed while at >270W and above >715 degrees C nanostructured pillars with large inter-pillar voids were produced. The latter appeared black and exhibited a strong {112}(T) texture with interpillar twist angles of +/- 8 degrees. Application of a negative dc bias of 0-50V to the film during growth was not found to alter the film morphology or stoichiometry. The results are interpreted as resulting from the plasma causing strong etching favoring formation of {112}(T) planes and preferential nucleation of new grains, balanced against conventional thermal diffusion and normal growth mechanisms at higher temperatures. The absence of effects due to applied substrate bias suggests that physical sputtering or ion bombardment effects were minimal. The nanostructured platelet and pillar films were found to exhibit less than one percent reflectivity at angles up to 75 degrees from the surface normal.

• 出版日期2013-10-21