The novel Al0.66In0.34As0.85Sb0.15/In0.53Ga0.47As heterostructure has a large conduction band offset (about 1 eV). Taking the advantage of high conduction-band offset, it has been demonstrated to be a potential candidate for double-barrier resonant tunneling diodes (DBRTDs). Well width is an important parameter for the performance of a DBRTD. We fixed the barrier width and discussed the well width dependence for Al0.66In0.34As0.85Sb0.15/In0.53Ga0.47As DBRTD. Peak current densities exhibit a maximum at the 4 mn well width. A peak-to-valley current ratio of 46 with a peak current density of 22 kA/cm(2) at room temperature was demonstrated for the 4 nm-InGaAs-well. (C) 2002 Published by Elsevier Science Ltd.