In/sub 0.29/Al/sub 0.71/As/In/sub 0.3/Ga/sub 0.7/As heterostructure devices grown on GaAs substrates with a metamorphic buffer design

By increasing the In composition in the In,Gal_,As channel, the so-called pseudomorphic channel on GaAs substrates can substantially improve the device performance due to a better carrier confinement and higher drift velocity. However, for further increasing the In content in the InxGal-,As channel is always limited by critical thickness. Therefore, the unstrained or so-called metamorphic layer design was proposed to break the limitation of critical thickness. This approach used the graded approach to gradually increase the In content in the buffer. As long as the interfacial dislocations are confined in this graded buffer, a dislocation-free and stress-free layer with a high In content can be obtained simultaneously on the top of this metamorphic buffer[l]. In this study, we used a step-garded In,Gai_,As buffer to increase the In composition up to x a . 3 0 on GaAs substrates, and fabricated various electronic devices based on this In0.2gQ.7 1As/Ino.3Gag.7As heterostructure.