Optimized channel thickness for high electron mobility in pseudomorphic In0.74Ga0.26As/In0.52Al0.48As quantum-well HEMT structures with (411)A super-flat interfaces grown by MBE

Thermal stability of Ti/Pt/Au ohmic contacts for cryogenically cooled InP-based HEMTs on (411)A-oriented substrates by MBE

“…We obtained an extremely high electron mobility (90; 500 cm 2 =Vs at 77 K) in an In 0:7 Ga 0:26 As=In 0:52 Al 0:48 HEMT structure on the (4 1 1)A InP substrate. It was 1.5 times higher than the corresponding (1 0 0) HEMT structure with similar sheet carrier concentration ðN s Þ$3 Â 10 12 cm À2 [5]. Such high mobility was due not only to suppressing interface roughness scattering because of (4 1 1)A super-flat interfaces but also suppressing remote impurity scattering because of a 9-nm-thick InAlAs spacer layer.…”

“…We grew two categories of the In 0:75 Ga 0:25 As=In 0:52 Al 0:48 As HEMT structures on the (4 1 1)A InP substrates by MBE, as shown in Table 1. The 8-nm-thick pseudomorphic In 0:75 Ga 0:25 As channel was used to enhance the mobility of two-dimensional electrons [5]. All InAlAs layers were lattice matched to the InP substrates.…”

Extremely high electron mobility of pseudomorphic In0.74Ga0.26As∕In0.46Al0.54As modulation-doped quantum wells grown on (411)A InP substrates by molecular-beam epitaxy

“…We have reported that "͑411͒A super-flat interfaces" (effectively atomically flat heterointerfaces over a wafer-size area) can be realized in QWs grown on ͑411͒A-oriented substrate by molecular-beam epitaxy (MBE) not only for GaAs/ AlGaAs systems on GaAs 5,6 but also for lattice-matched and pseudomorphic InGaAs/ InAlAs systems on InP. 7, 8 We also reported that a pseudomorphic In 0.74 Ga 0.26 As/ In 0.52 Al 0.48 As MD-QW with the ͑411͒A super-flat interface shows 2DEG mobility of 90 500 cm −2 / V s with a sheet electron concentration ͑N s ͒ of 3.1ϫ 10 12 cm −2 at 77 K. 9 Large Al content of an InAlAs barrier layer is very effective to achieve high 2DEG mobility in the InGaAs/ InAlAs MD-QW, because a larger conduction-band discontinuity ͑⌬E c ͒ results in stronger confinement of electrons in the QW channel. Furthermore, the compressive strain of the In 0.74 Ga 0.26 As channel layer can be compensated with the tensile stained In 1−y Al y As barriers ͑y Ͼ 0.48͒.…”

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

“…8) The 8-nm-thick pseudomorphic In 0:75 Ga 0:25 As channel was used to enhance the electron mobility of twodimensional electron gas (2DEG). 9) The gate-to-channel distance of 13 nm was also designed so as not to decrease the sheet electron concentration (N s ) in order to reduce the source and drain resistances and increase g m and f T . 10) Electron mobility () and N s were measured by Hall effects under a magnetic field of 0.32 T for the (411)A and (100) samples.…”