Carbon Atomic Layer Doping in AlGaAs by Metalorganic Chemical Vapor Deposition and Its Application to a P-Type Modulation Doped Structure

Carbon (C) atomic layer doping in AlGaAs is demonstrated. During undoped AlGaAs growth by conventional low-pressure metalorganic chemical vapor deposition, C atomic layer doping is performed by supplying trimethylgallium onto AlGaAs surfaces under arsine-free conditions. C incorporation increases with increasing Al composition of the surface layer onto which trimethylgallium is supplied, suggesting that the C incorporation mechanism is that As atoms of the AlGaAs surface are partially replaced by C atoms of methyl groups to become acceptors. The capacitance-voltage measurement of the C atomic layer doped AlGaAs shows a carrier profile with a full width at half-maximum as narrow as 8.0 nm at a peak carrier concentration of 2.1×1018 cm-3, indicating that the diffusion of C atoms in AlGaAs is not serious during growth at 610°C. A p-type modulation doped AlGaAs/GaAs structure was fabricated using C atomic layer doping, and a mobility of 1.3×105 cm2/V·s was obtained at 1.5 K for a sheet hole density of 3.9×1011 cm-2. Because of the high quality two-dimensional hole gas, a region limited by acoustic phonon scattering can be seen in the temperature dependence of hole mobility.