Diffusion Studies of the Si delta-doped GaAs by Capacitance- Voltage Measurement.

Using triethylgallium and arsine, high quality GaAs can be grown at a relatively low substrate temperature of 500C by chemical beam epitaxy. Such low temperature has the advantage of negligible Si diffusion effect. Capacitance-voltage (CV) measurement of the Si delta-doped GaAs shows extremely narrow profile width of 22angstroms at 300K and 18angstroms at 77K, 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 high growth temperature of ~600C employed in conventional molecular beam epitaxy. The CV widths of the annealed delta-doped structures also provide an excellent measure to determine the Si diffusion constant in GaAs.