Role of Surface Orientation on Atomic Layer Deposited Al2O3/GaAs Interface Structure and Fermi Level Pinning: A Density Functional Theory Study

Ganesh Hegde, Purdue University, Network for Computational Nanotechnology
Gerhard Klimeck, Purdue University, Network for Computational Nanotechnology
Alejandro Strachan, Purdue University - Main Campus

Date of this Version



Appl. Phys. Lett. 99, 093508 (2011); doi: 10.1063/1.3624897


Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters: Volume 99, Issue 9 and may be found at The following article has been submitted to/accepted by Applied Physics Letters. Copyright (2011) Ganesh Hegde, Gerhard Klimeck, and Alejandro Strachan. This article is distributed under a Creative Commons Attribution 3.0 Unported License.


We investigate the initial surface reaction pathways in the atomic layer deposition (ALD) of Al2O3 on GaAs (111)A and (111)B substrates using precursors trimethylaluminum (TMA) and water to ascertain the effect of surface orientation on device performance. We find that the condition of the respective substrates prior to deposition of TMA and water has a major impact on the surface reactions that follow and on the resulting interface structure. The simulations explain the atomistic mechanism of the interfacial self-cleaning effect in ALD that preferentially removes As oxides. The electronic structure of the resulting atomic configurations indicates states throughout the bandgap for the (111)B structure. By contrast, the (111)A structure has no states in the mid-gap region, thus explaining the significant experimental difference in Fermi Level Pinning behavior for corresponding devices.


Nanoscience and Nanotechnology