Measurement of Alloy Content in GaN and Related Materials

FIGURE 1 X-ray oliffraction peak positions of the (In/Al)xGai.xN alloys grown by MBE. 

Nominal composition Peak position (20) Calc, composition (%) EPMA composition (%) 

Kovarsky et al have used the SIMS method to determine the mole fraction in InGaN [8], Their technique is based on a comparison of the relative signal intensities of CsM+ (M = In, Ga) and does not require reference samples. The SIMS results were independently confirmed by XRD, energy dispersive X-ray fluorescence spectroscopy, EPMA and SNMS, and the absolute value of the InN mole fraction has a relative accuracy 15%. 

FIGURE 2 Variation of the energy bandgap of InxGai xN over the entire compositional range of 0 x 1 (after [8]). 

With the use of the MCs+ technique to reduce matrix effects in SIMS, Gao et al measured the composition of InxGai.xN alloys and confirmed the validity of this technique with the RBS method [12], It was shown that the SIMS-MCs+ method can provide very accurate measurements of composition on complex structures and devices [13], 

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A9.2 Measurement of alloy content in GaN and related materials TABLE 1 Alloy compositions calculated by XRD and EPMA. 

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