Striped-channel InAlAs/InGaAs HEMTs with shallow-grating structures

Striped-channel (SC) InAlAs/InGaAs HEMTs have been demonstrated with shallow gratings. The shallow grating structure keeps the gate from touching the channel layer and thus solves the gate leakage problem observed in the deep grating devices on InP substrates. Various channel widths have been realized to study the impact of the channel width on the dc and microwave performance. Due to the enhanced charge control in the SC HEMTs, enhanced transconductance/source-drain current (G/sub m//I/sub ds/) and transconductance/output conductance (G/sub m//G/sub ds/) were observed. Compared with conventional HEMTs, the SC HEMTs showed degraded f/sub T/ due to additional parasitic capacitances and improved f/sub max/ due to better carrier confinement.