AVS 59th Annual International Symposium and Exhibition
    In Situ Microscopy and Spectroscopy Focus Topic Wednesday Sessions
       Session IS+AS+OX+ET-WeM

Paper IS+AS+OX+ET-WeM9
In Situ Studies of Al2O3 ALD Growth and Self-cleaning on III-V Surfaces by STM and XPS

Wednesday, October 31, 2012, 10:40 am, Room 007

Session: In Situ Characterization of Solids: Film Growth, Defects, and Interfaces
Presenter: L.N.J. Rodriguez, IMEC, Belgium
Authors: L.N.J. Rodriguez, IMEC, Belgium
A. De Clercq, IMEC, Belgium
M. Tallarida, BTU Cottbus, Germany
D. Cuypers, IMEC, Belgium
J.P. Locquet, KU Leuven, Belgium
S. Van Elshocht, IMEC, Belgium
C. Adelmann, IMEC, Belgium
M. Caymax, IMEC, Belgium
Correspondent: Click to Email
A custom built ALD UHV-compatible reactor has been used to study the growth of TMA on InP and InAlAs by STM in conjunction with additional studies performed in a reactor attached to a synchrotron XPS. The effects of selected ex-situ cleans has been measured along with the subsequent cycles of ALD growth from TMA and water. The STM data shows morphological differences between the ex-situ cleans on InP, with sulphuric acid cleans yielding plateaus but ammonium sulphide cleans yielding rough surfaces. In-situ measurements of these surfaces after TMA dosing shows the growth of islands which converge to film closure after ten cycles of ALD growth. In-situ measurements of the I-V curves by STS allowed the creation of bandgap maps of the III-V interfaces after TMA dosing. These bandgap maps showed a non-uniform distribution with regions of either higher or lower bandgap. The mean bandgap was seen to decrease with increasing numbers of ALD cycles. In-situ XPS data on similar systems showed a reduction in surface oxides for InAlAs but not for InP. The reduction of arsenic oxides with a creation of metallic arsenic, along partial reduction of indium oxides and a conversion of aluminium sub-oxides to aluminium oxide was seen in the former case. In the latter case, a formal oxidation of the phosphorus was seen with increased TMA dosing instead of a self-cleaning effect.