Highly strained In0.33Ga0.67As/AlAs‐based resonant tunneling diodes have been fabricated on GaAs(100) substrates without the use of thick strain relieving buffer layers. These structures exhibit a simultaneously high peak current density (Jp) of 125 kA/cm2and a peak to valley ratio (PVR) of 4.7. A PVR of 5.9 withJp=73 kA/cm2is observed on some devices, the highest PVR seen for such devices. The excellent resonant tunneling characteristics of these devices are attributed to accurate device design using a &Ggr;‐X‐&Ggr;‐X‐&Ggr; resonant tunneling path and to high quality interfaces obtained through the use of optimized growth conditions.