Title :
High-quality CdTe films from nanoparticle precursors
Author :
Schulz, Douglas L. ; Pehnt, Martin ; Urgiles, Ed ; Niles, David W. ; Jones, Kim M. ; Curtis, Calvin J. ; Ginley, David S.
Author_Institution :
Nat. Renewable Energy Lab., Golden, CO, USA
Abstract :
In this paper we demonstrate that nanoparticulate precursors coupled with spray deposition offers an attractive route into electronic materials with improved smoothness, density, and lower processing temperatures. Employing a metathesis approach, cadmium iodide was reacted with sodium telluride in methanol solvent, resulting in the formation of soluble NaI and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe thin film formation was achieved by spray depositing the nanoparticle colloids (25-75 Å diameter) onto substrates at elevated temperatures (T=280-440°C) with no further thermal treatment. These films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Cubic CdTe phase formation was observed by XRD, with a contaminant oxide phase also detected. XPS analysis showed that CdTe films produced by this one-step method contained no Na or C and substantial O. AFM gave CdTe grain sizes of ~0.1-0.3 μm for film sprayed at 400°C. A layer-by-layer film growth mechanism proposed for the one-step spray deposition of nanoparticle precursors will be discussed
Keywords :
II-VI semiconductors; X-ray diffraction; X-ray photoelectron spectra; atomic force microscopy; cadmium compounds; coatings; colloids; grain size; nanostructured materials; nanotechnology; semiconductor growth; semiconductor materials; semiconductor thin films; spray coating techniques; spray coatings; 0.1 to 0.3 micron; 25 to 75 A; 280 to 440 C; CdTe; X-ray diffraction; X-ray photoelectron spectroscopy; XPS; XRD; atomic force microscopy; density; electronic materials; high-quality CdTe films; layer-by-layer film growth mechanism; lower processing temperatures; nanoparticle precursors; one-step spray deposition; thermal treatment; Atomic force microscopy; Cadmium compounds; Chemicals; Methanol; Nanoparticles; Solvents; Sputtering; Temperature; Thermal spraying; X-ray scattering;
Conference_Titel :
Photovoltaic Specialists Conference, 1996., Conference Record of the Twenty Fifth IEEE
Conference_Location :
Washington, DC
Print_ISBN :
0-7803-3166-4
DOI :
10.1109/PVSC.1996.564281
