Diffusion studies of the Si δ-doped GaAs by capacitance-voltage measurement

Using triethylgallium and arsine, high-quality GaAs can be grown at a relatively low substrate temperature of 500 °C by chemical beam epitaxy. Such a low temperature has the advantage of a negligible Si diffusion effect. Capacitance-voltage (C-V) measurements of the Si δ-doped GaAs show extremely narrow profile widths of 22 Å at 300 K and 18 Å at 77 K, indicating a very high degree of Si spatial localization has been achieved. The subsequent annealing experiments reveal that significant Si segregation and diffusion exist at a high growth temperature of ∼600 °C, usually employed in conventional molecular-beam epitaxy. The C-V widths of the annealed δ-doped structures also provide an excellent measure to determine the Si diffusion constant in GaAs.