Abstract
Experimental results, related to a novel laser-assisted technique for deposition of III-V semiconductor thin-films, are presented. The method involves precursors in the form of I-III- V Zintl-phase materials. While such compounds exhibit a variety of useful properties, the presence of the group I element is a major concern--in terms of the desired final product it can be considered a major impurity that has to be removed. To address this situation, we employ a strategy, based on the difference in the ionization potentials for the constituent elements, that can be described in brief as (1) laser ablation of a I-III-V compound, (2) removal of the group I element by selective gas-phase laser ionization and extraction in an electric field, and (3) subsequent re-deposition of the III-V compound. For a particular I-III-V Zintl-phase compound, potassium indium antimonide, K4In4Sb6, time-of-flight mass spectra clearly demonstrate high yield selective gas phase ionization and removal of potassium from the ablation plume. Deposition conditions have been found for scaling of the above removal process macroscopically to thin film growth. The deposits have been studied by Auger electron spectroscopy and the results confirm significant depletion of potassium from thin films deposited via the proposed ablation/ionization removal technique. An assessment is made as to the viability of the process and implications for possible applications of this research as related to film growth are discussed.
