## 초록

A gate recess process was developed to control the gate recess depth and the short lateral etching width for device fabrication, and a metamorphic HEMT (MHEMT) device with an 80-nm T-shaped gate was demonstrated using this gate recess process. A reduced lateral recess width of 53-nm was obtained on the etch side of a T-shaped gate for the gate recess process. The DC and the microwave characteristics of 80-nm MHEMT devices with In$_{0.53}$Ga$_{0.47}$As channels was investigated. The 80 nm $\times$ 100 $\mu$m MHEMT device showed a high gate-to-drain breakdown voltage of $-$7.5 V, an extrinsic transconductance of 900 mS/mm, and a threshold voltage of $-$0.6 V. The obtained cut-off frequency and maximum frequency of oscillation were 230 GHz and 300 GHz, respectively. This excellent device performance is attributed to the reduced gate length and lateral recess width for this device fabrication process.

A gate recess process was developed to control the gate recess depth and the short lateral etching width for device fabrication, and a metamorphic HEMT (MHEMT) device with an 80-nm T-shaped gate was demonstrated using this gate recess process. A reduced lateral recess width of 53-nm was obtained on the etch side of a T-shaped gate for the gate recess process. The DC and the microwave characteristics of 80-nm MHEMT devices with In$_{0.53}$Ga$_{0.47}$As channels was investigated. The 80 nm $\times$ 100 $\mu$m MHEMT device showed a high gate-to-drain breakdown voltage of $-$7.5 V, an extrinsic transconductance of 900 mS/mm, and a threshold voltage of $-$0.6 V. The obtained cut-off frequency and maximum frequency of oscillation were 230 GHz and 300 GHz, respectively. This excellent device performance is attributed to the reduced gate length and lateral recess width for this device fabrication process.