Nonlinear decomposition of gallium x-ray induced Auger transitions: A new path to quantify gallium-based III–V materials

Interest in Ga-based III–V semiconductors has grown in many applicative domains such as solar applications or power electronics. However, using the conventional Al Kα XPS source (most commonly used irradiation) on GaN materials leads to an overlap between photopeaks and Auger lines, complicating the interpretation, especially the quantification which requires to separate the Ga L2M4.5M4.5 Auger line and the N 1s photopeak signals. In this paper, we propose an upstream study to develop a meticulous decomposition procedure to address this issue. This procedure relies on the joint decomposition of the twin Ga L2M4.5M4.5 and Ga L3M4.5M4.5 X-AES lines based on the nonlinear least square decomposition model with realistic decomposition parameters adjusted on a reference Ga–As binary alloy exempted from N and oxide. In addition, a similar procedure has been developed on a Ga2O3 reference to consider any oxide presence, Ga-based alloys being hardly prone to rapid surface oxidation. A complete decomposition has been evaluated on three Ga binary alloys, namely, GaAs, GaP, and GaSb, all presenting a small native oxide on the surface. A coherent separation between the alloy and oxide environments is demonstrated, even for ultrathin oxide layers and a remarkable reproducibility of the decomposition pattern for the alloy phase, whatever the nature of the III–V binary alloy. Quantification is made using either photopeaks or Auger transitions and good agreement of the alloy ratio Ga/V element is found in any case. These preliminary results are auspicious for further implementation of this methodology on N-containing Ga compounds.