Effects of Heterointerface Flatness on Device Performance of InP-Based High Electron Mobility Transistor

Abstract

We achieved a current gain cutoff frequency ( f T ) of 310 GHz at a cryogenic temperature (16 K) in a 195-nm-long gate In 0:75 Ga 0:25 As/In 0:52 Al 0:48 As high-electron-mobility transistor (HEMT) fabricated on a (411)A-oriented InP substrate. This is 27% higher than that at room temperature (245 GHz). For a corresponding HEMT fabricated on a (100) InP substrate, f T of 268 GHz was also obtained at 16 K, which is 15% higher than that obtained at 300 K (233 GHz). For both (411)A and (100) HEMTs, this significant enhancement in low-temperature f T s was caused by the increased average electron velocity under the gate (v ave ), which was mainly due to the suppression of phonon scattering. Furthermore, f T as high as 310 GHz was attributed to v ave of up to 4:9 Â 10 7 cm/s at 16 K for the (411)A HEMTs. This is higher than that of the (100) HEMTs (4:5 Â 10 7 cm/s) and is due to the reduced interface roughness scattering of electrons caused by (411)A super-flat InGaAs/InAlAs interfaces (effectively atomically flat heterointerfaces over a wafer-size area).

Si‐Doping Effects in AlGaN Channel Layer on Performance of N‐Polar AlGaN/AlN FETs

“…It is assumed that the improved flatness reduces the interface roughness scattering of the electrons. [ 26 ]…”

“…It is assumed that the improved flatness reduces the interface roughness scattering of the electrons. [26] The surface condition was changed by Si doping, which may have been because of the Si which acts as an antisurfactant. [27] Because the N-polar Al 0.1 Ga 0.9 N has a large step structure, as shown in Figure 4b, we speculate that in N-polar Si-Al 0.1 Ga 0.9 N with a Si-doping depth of 2.5-17.5 nm, Si prevents nuclei expansion in the nucleation stage, resulting in improved flatness.…”

Realization of Wurtzite GaSb Using InAs Nanowire Templates

“…As mentioned briefly in the Introduction, the heterointerface quality is of importance in device performance, and also of interest in studies investigating various quantum phenomena . Therefore, in the following we thoroughly investigate the material composition and crystal quality of the heterointerfaces in our wurtzite InAs–GaSb(–InAs) core–shell(–shell) nanowires, namely the radial interfaces between wurtzite InAs core and GaSb shell, and between the GaSb shell and the outer InAs shell.…”