Sub-threshold characteristics of the 0.2 /spl mu/m capless InP/In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As p-HEMTs having a self-aligned gate

Sub-threshold characteristics of a 0.2 /spl mu/m self-aligned gate (SAG) capless InAlAs/InGaAs p-HEMT having a highly strained InAs sub-channel were investigated. The extracted I/sub ON//I/sub OFF/ ratio and sub-threshold slope of the SAG capless HEMT (1.27/spl times/10/sup 4/ and 78 mV/dec) was better than those of the conventional recessed p-HEMT (5.1/spl times/10/sup 3/ and 120 mV/dec), respectively. The capless p-HEMT showed an I/sub ON//I/sub OFF/ ratio twice larger than that of the conventional recessed p-HEMT having a heavily doped InGaAs cap layer. Even without the heavily n-doped InGaAs cap layer, the 0.2 /spl mu/m SAG capless p-HEMT showed the maximum g/sub m/, f/sub T/, and v/sub sat/ (saturation velocity) of 1.12 S/mm, 185 GHz, and 3.3/spl times/10/sup 7/ cm/sec, respectively.