Electrical properties of Si-doped GaAs layers grown on (411)A GaAs substrates by molecular beam epitaxy (MBE) were investigated for applications to GaAs/AlGaAs resonant tunnelling diodes with atomically flat (411)A GaAs/AlGaAs interfaces over an entire device area. These flat interfaces can be realized by MBE under certain growth conditions (growth temperature Ts=580°C and V/III pressure ratio of less than or equal to 11). When the V/III pressure ratio is high (above 15) for Ts=580°C, Si-doped GaAs on a (411)A substrate showed an n-type conduction similar to conventional Si-doped GaAs on (100) substrates. (411)A GaAs/AlGaAs interfaces grown under this condition, however, cannot become as flat and as superior as conventional (100) GaAs/AlGaAs interfaces. On the other hand, when the V/III pressure ratio is 7, an Si-doped GaAs layer on (411)A showed p-type conduction. In the case of a V/III pressure ratio of 10.5 and Ts=580°C, Si-doped GaAs still showed n-type conduction with the compensation ratio ν (≡(ND+NA)/(ND-NA)) = 2.3. This result suggests that Si can be used as an n-type dopant in GaAs for GaAs/AlGaAs resonant tunnelling diodes grown on (411)A GaAs substrates with atomically flat (411)A GaAs/AlGaAs interfaces.
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