Fabrication of 150-nm T-Gate Metamorphic AlInAs/GaInAs HEMTs on GaAs Substrates by MOCVD

摘要

Metamorphic AlInAs/GaInAs high-electron-mobility transistors (HEMTs) of 150-nm gate length with very good device performance have been grown by metal–organic chemical vapor deposition, with the introduction of an effective multistage buffering scheme. By using a combined optical and e-beam photolithography technology, submicrometer mHEMT devices have been achieved. The devices exhibit good dc and RF performance. The maximum transconductance was 1074 mS/mm. The nonalloyed ohmic contact resistance $R_{c}$ was as low as 0.02 $Omega cdot hbox{mm}$. The unity current gain cutoff frequency $(f_{T})$ and the maximum oscillation frequency $(f_{max})$ were 279 and 231 GHz, respectively. This device has the highest $f_{T}$ yet reported for 150-nm gate-length HEMTs. Also, an input capacitance to gate–drain feedback capacitance ratio $C_{rm gs}/C_{rm gd}$ of 3.2 is obtained in the device.