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

For carbon-doped p-GaAs layers grown by metalorganic vapor-phase epitaxy (M OVPE), the two parameters, k and alpha, respectively, used for indicating s train state and activity ratio of the C-doped epilayers, are important for demonstrating the quality of GaAs : C layers. By comparing the data from Ha ll 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 tetrachl oride (CCl4), the lattice mismatch and resultant strain state, and hydrogen passivation of GaAs : C layers on GaAs substrates were investigated as wel l 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)k p/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 spec trometry (SIMS), is not only relatively simple and cheap, but also in fairl y good agreement with the experimental results. (C) 1999 Elsevier Science B .V. All rights reserved.