A recessed-gate In0.52Al0.48As/n+-In0.53 Ga 0.47As MIS-type FET

Scaling of the In_0.52 Al_0.48As insulator thickness of In_0.52 Ga_0.48As/n⁺ In_0.53 Ga_0.47As MIS (Metal insulator semiconductor) type FETs (field effect transistors) is found experimentally to result in a drastic drop in performance below 200 Å. This is demonstrated to arise from an increase in the sheet resistance of the extrinsic portions of the device that accompanies insulator scaling. In order to solve this problem, a recessed-gate MISFET with a very thin (300 Å) n⁺-In_0.53 Ga _0.47As cap layer has been fabricated. A 1.5-μm-long gate device showed a transconductance of 285 mS/mm and a current-gain cutoff frequency of 19.4 GHz. This result proves the ability of a thin n⁺ -In_0.53 Ga_0.47As cap to reduce source resistance and improve device performance. It is concluded that the fabricated recessed-gate structure is a promising candidate for high-performance-scaled MIS-type FETs based on thin, heavily doped In _0.53 Ga_0.47As channels