Composition Verification of AlGaAs Epitaxial Layers using Inductively Coupled Plasma Optical-Emission Spectroscopy

Published

September 28, 2003

Author(s)

Kristine A. Bertness, Todd E. Harvey, Albert J. Paul, Larry Robins, Gregory C. Turk, Therese A. Butler, Marc L. Salit

Abstract

We have applied an analytical chemistry method, inductively coupled plasma optical-emission spectroscopy (ICP-OES), to increase the accuracy of composition measurement of AlGaAs epitaxial thin films. ICP-OES results were compared with composition determination from photoluminescence (PL) spectra based on a newly developed correlation equation [1] between peak luminescence energy and film composition. This correlation was based on electron microprobe analysis and reflection high-energy electron diffraction (RHEED) growth rate measurements. Although ICP-OES is a destructive method, it has high absolute accuracy with results directly traceable to the mole. The AlGaAs films used in this study were grown using molecular beam epitaxy to a thickness of 3 mm. The composition was determined near the time of film growth from RHEED oscillation measurements of the individual AlAs and GaAs growth rates using methods[2] designed to optimize the accuracy and precision of this technique. The films were characterized after growth using PL and ICP-OES. PL measurements included lateral uniformity assessment and temperature corrections for deviations from a standard sample temperature of 298.3 K. ICP-OES specimens were prepared by dissolving the AlGaAs film in a mixture of sulphuric acid, hydrogen peroxide, and water. In order to avoid contamination from the GaAs substrate, the films were either transferred first to silicon substrates using epitaxial lift-off or grown on Ge substrates. We observed that for most specimens, the three methods agree to within their stated uncertainties (two standard-deviation definition), ranging from 0.0015 to 0.012, particularly near 0.20 Al mole fraction. The largest deviations between the RHEED and PL measurements were most likely due to drift in Ga flux over time. This work was part of a program to offer standard reference materials of AlGaAs films on GaAs for use in establishing standardized composition measurement in III-V semiconductor alloys.

Conference Dates

September 28-October 2, 2003

Conference Location

Keystone, CO, USA

Conference Title

North American Conf. on Molecular Beam Epitaxy (NAMBE 2003)

Pub Type

Conferences

Keywords

AlGaAs, composition standards, photoluminescence, reflection high energy electron diffraction (RHEED)

Citation

Bertness, K. , Harvey, T. , Paul, A. , Robins, L. , Turk, G. , Butler, T. and Salit, M. (2003), Composition Verification of AlGaAs Epitaxial Layers using Inductively Coupled Plasma Optical-Emission Spectroscopy, North American Conf. on Molecular Beam Epitaxy (NAMBE 2003), Keystone, CO, USA (Accessed April 19, 2024)