We propose an unstrained Al0.66In0.34As0.85Sb0.15/In-0.53 Ga0.47As heterost
ructure for double-barrier resonant tunneling diode. A peak-to-valley curre
nt ratio of 22.3 and a peak current density of 8.9 kA/cm(2) were achieved f
or the unstrained Al0.66In0.34As0.85Sb0.15/In0.53Ga0.47As double-barrier tu
nneling diode at room temperature.