Determination of Thickness and Composition of Thin Al_xGa_1-xAs Films on GaAs substrates by Total Electron Yield (Tey) Measurements

Abstract

In our paper “Determination of thickness and composition of thin AlxGa1-xAs layers on GaAs by total electron yield (TEY)” we described the principles of the determination of thickness t and Al concentration x employing TEY. The essential experimental quantities are the absorption edge jumps of the-eleraents measured in TEY-mode:Since the problem asks for the quantification of two unknowns (x,t), at least two TEYjumps are needed. The K jumps of Al and Ga deliver reliable information. From the theoretical approach1,2 of quantitative TEY a nearly linear relationship between the measured TEY jumps and the composition (in wt%) has to be expected. The As concentration varies over the interesting composition range 0<x<0.6 from approximately 50 to 60wt% and causes a similar variation of the TEY jump versus x. In combination with the statistical significance of the experimental data we neglect the TEY K jump information from As.

Quantitative analysis by X-ray induced total electron yield (TEY) compared to XRFA

“…The half-width of 40 eV at photon energy of 10 keV of the setup of Figure 2 is responsible for the occurrence of weak XANES signals in the TEY response at photon energies above the Cr–K edge of Figure 1. The influences of statistical errors, spectral width of the monochromatic X-ray beam, and the energy range of linear least squares fits on the significance and detection limits of TEY were treated in earlier investigations (Ebel et al , 1997; 1997; 1997; 1998; 1999; 1999; 2000; 2001).…”

“…Figure 6 provides experimental relative jumps (crosses) and theoretical values (squares) in dependence on the Al concentration. For computations the thicknesses and compositions as given by the supplier of the Al x Ga 1−x As layers were used (Ebel et al , 1997; 1997; 1995; 1995; 2002). Further investigations on quantitative TEY were performed on the binary alloy systems Au–Cu (Ebel et al , 1995; 1995), Au–Pd (Ebel et al , 1997) and a basic contribution to quantitative TEY was made by Ghassemi (2003).…”

“…Another application of TEY are thickness determinations of thin layers (Ebel et al , 1997; 1997; 1998; 1999; 1999; 1995; 1995; 2002; 1994; 1996; 1997; 1999; 2001). The principle of thickness determinations by information from layer signals is shown on the example of thin Cr layers on Fe substrates.…”