Characterization of carbon-doped GaAs grown by metalorganic vapor-phase epitaxy

For carbon-doped p-GaAs layers grown by metalorganic vapor-phase epitaxy (MOVPE), the two parameters, k and alpha, respectively, used for indicating strain state and activity ratio of the C-doped epilayers, are important for demonstrating the quality of GaAs : C layers. By comparing the data from Hall effect and double-crystal X-ray diffraction (DCXRD) measurements made on as-grown and annealed GaAs : C layers grown by atmospheric pressure MOVPE (AP-MOVPE) using trimethylgallium (TMGa), arsine (AsH3) and carbon tetrachloride (CCl4), the lattice mismatch and resultant strain state, and hydrogen passivation of GaAs : C layers on GaAs substrates were investigated as well as their changes after annealing. Furthermore, a relation was established between the lattice mismatch (Delta a(perpendicular to)/a(GaAs)) and hole concentration p (cm(-3)), Delta a(perpendicular to)/a(GaAs) = -8 x 10(-24)kp/alpha. With this equation the relation between k and a can be determined from the relation between the measured (Delta a(perpendicular to)/a(GaAs)) and p. If one of the two parameters, k and alpha, is known, the other could be just then determined. This method for determining the values of both k and alpha, not involving the traditional use of the secondary ion mass spectrometry (SIMS), is not only relatively simple and cheap, but also in fairly good agreement with the experimental results. (C) 1999 Elsevier Science B.V. All rights reserved.