AVS 52nd International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoP

Paper AS-MoP13
Random Fractal Behavior of InGaAs Quantum Dots Using AFM

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Aspects of Applied Surface Science Poster Session
Presenter: X. Qian, University of Massachusetts
Authors: X. Qian, University of Massachusetts
S.R. Vangala, University of Massachusetts
C. Santeufemio, University of Massachusetts
W.D. Goodhue, University of Massachusetts
Y. Park, Inje University, South Korea
Correspondent: Click to Email
Autocorrelation, height-height difference correlation, and power spectral density (PSD) analysis techniques have been applied to AFM scans of semiconductor materials for years. Recently Fenner et al@footnote 1@ and Krishnaswami et al@footnote 2@ have developed and applied random fractal analysis techniques to AFM image statistics in order to determine the fractal nature of semiconductor surfaces. Here random fractals are used to investigate InGaAs quantum dots. An uncapped single layer InGaAs dot structure exhibited an autocorrelation Hurst parameter of approximate 0.67 with an autocorrelation length of 90 nm and height-height difference correlation length of 56 nm. An uncapped InGaAs dot structure with two buried InGaAs dot layers exhibited an autocorrelation Hurst parameter of approximate 0.45 with an autocorrelation length of 70 nm and height-height difference correlation length of 47 nm. A 220 nm capped three layers InGaAs dot structure on the other hand exhibited an autocorrelation Hurst parameter of approximate 0.9 with an autocorrelation length of 190 nm and height-height difference correlation length of 130 nm. All samples exhibited height-height difference Hurst parameters and power spectral density Hurst parameters of 1 (indicating Gaussian distributions). All images analyzed were 10x10 µm@super 2@ in size. The analysis indicates that as more dot layers are incorporated in the structure, the fractal nature of the over layer increases. This nature is reversed by a thick capping layer. @FootnoteText@ @footnote 1@ D.B. Fenner, J. Appl. Phys., 95(10),5408-5418 (2004)@footnote 2@ K. Krishnaswami, Mater. Res. Soc. Symp. Proc. Vol.829 (2005).