Enhanced device performance by unstrained In/sub 0.3/Ga/sub 0.7/As/In/sub 0.29/Al/sub 0.71/As doped-channel FET on GaAs substrates

An alternative In/sub 0.3/Ga/sub 0.7/As/In/sub 0.29/Al/sub 0.71/As heterostructure based on GaAs is proposed, which provides a large conduction-band discontinuity for a better carrier confinement, resulting in a high-carrier density. This unstrained high-In channel achieved a better device performance, as compared with the conventional pseudomorphic channel, which is always limited by the critical thickness. This unstrained channel is also proven to be more stable after a long-term biased-stress.