Effect of Si doping in AlAs barrier layers of AlAs-GaAs-AlAs double-barrier resonant tunneling diodes

AlAs-GaAs-AlAs double-barrier resonant tunneling diodes (DBRTDs) with different doping levels in the AlAs layers have been investigated. Two-step spacer layers were used in all samples. Peak-to-valley current ratios (PVCRs) as high as 3.5 (11.3), 3.5 (11.3), and 2.7 (8.2) were observed at 300 K (77 K) for samples with undoped, 1.2×1017 cm−3, and 3×1018 cm−3 doped AlAs barriers, respectively. These results indicate that resonant tunneling is not strongly affected by ionized Si atoms in the AlAs barriers. The excellent PVCRs observed in DBRTDs with two-step spacer layers is not because of low background impurity densities in the active region, but because of a third barrier formed by band bending in the spacer layers.