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.