Characterization of hydrogen passivation and carbon self-compensation of highly C-doped GaAs by means of x-ray diffraction

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Abstract
Highly C‐doped GaAs epilayers grown by low‐pressure metalorganic vapor phase epitaxy were studied using high‐resolution x‐ray diffraction. An x‐ray diffraction simulation program based on the dynamical theory has been developed, such that the carbon self‐compensation effect and the passivation due to the interstitially incorporated hydrogen in the C‐doped GaAs can be taken into account. While the (004) Bragg reflection can only be used to measure the lattice contraction caused by carbon doping, the (002) Bragg reflection is highly sensitive to the carbon occupation of the gallium or arsenic sublattice, respectively. Fitting of the simulated diffraction curves of both the (004) and the (002) reflections to the experimental ones enables the evaluation of the interstitially incorporated hydrogen concentration, and hence allows the calculation of the total carbon concentration and the net hole concentration. This technique was successfully applied to various C‐doped GaAs samples and the determined data were proven by Hall measurements and secondary‐ion mass spectrometry results.