The authors investigate the current-voltage characteristics Of In0.3Ga0.7As/In0.29Al0.71As double-barrier resonant tunnelling diodes grown on GaAs substrates. These devices exhibit peak-to-valley current ratios as high as 7.6 and 19.5 at room temperature and 77K, respectively. Two negative differential resistance regions are also observed for devices with larger well width. These results have shown that a high quality epilayer can be obtained despite the large lattice mismatch between In0.3Ga0.7As and GaAs.
