Zinc delta doping of GaAs by organometallic vapor phase epitaxy

Abstract
Zinc delta-doped layers have been grown by atmospheric pressure organometallic vapor phase epitaxy. Secondary-ion mass spectroscopy and electrochemical capacitance-voltage profiling were used to measure the spatial distribution of the Zn for both as-grown and annealed samples. The narrowest atomic profiles had full width at half maxima of 70 Å for peak Zn concentrations of ≤3×1018 cm−3. The as-grown width of these profiles is attributed to a combination of dopant memory effect and growth-related diffusion during the actual formation of the delta-doped layer. An effective diffusion coefficient D of ≤7×10−17 cm2/s is estimated for a growth temperature of 625 °C. Rapid thermal annealing at 900 °C for 5 s of several samples grown under various conditions led to calculated values of D in the range 0.5–1.0×10−12 cm2/s.