MBE-grown GaAs:Si/GaAs:Be tunnel diodes for multijunction solar cells

We present the results of optimization of the design and molecular beam epitaxy (MBE) growth technology of N-AlGaAs:Si/n +-GaAs:Si/p +-GaAs:Be/P-AlGaAs:Be heterostructures for tunnel diodes (TDs). The achieved maximum peak current density level (J p = 513 A/cm2) allows these TDs to be used for cascade connections both in multijunction solar cells and in structures of tunnel-coupled laser diodes. The initial region of the J–U curve of TDs exhibits nonlinearity that is explained by a residual potential barrier left in the p +–P–p + isotype heterojunction (confining the active region of TD) as a result of non-optimum doping of Al0.4Ga0.6As alloy.