Optimization studies of HgSe thin film deposition by electrochemical atomic layer epitaxy (EC-ALE)

Abstract

Studies of the optimization of HgSe thin film deposition using electrochemical atomic layer epitaxy (EC-ALE) are reported. Cyclic voltammetry was used to obtain approximate deposition potentials for each element. These potentials were then coupled with their respective solutions to deposit atomic layers of the elements, in a cycle. The cycle, used with an automated flow deposition system, was then repeated to form thin films, the number of cycles performed determining the thickness of the deposit. In the formation of HgSe, the effect of Hg and Se deposition potentials, and a Se stripping potential, were adjusted to optimize the deposition program. Electron probe microanalysis (EPMA) of 100 cycle deposits, grown using the optimized program, showed a Se/Hg ratio of 1.08. Ellipsometric measurements of the deposit indicated a thickness of 19 nm, where 35 nm was expected. X-ray diffraction displayed a pattern consistent with the formation of a zinc blended structure, with a strong (1 1 1) preferred orientation. Glancing angle fourier transform infrared spectroscopy (FTIR) absorption measurements of the deposit suggested a negative gap of 0.60 eV.