InP/In xGa 1− xAs (0.53⩽ x⩽0.81) high electron mobility transistor structures grown by solid source molecular beam epitaxy

Abstract

The effect of varying In mole fraction from x=0.53–0.81 in In x Ga 1− x As channel layer of InGaAs/InP high electron mobility transistor (HEMT) structure was studied by Hall measurements, photoluminescence spectroscopy and Raman scattering measurements. When x=0.75 a maximum electron mobility of 6130 and 35 600 cm 2/V s at 300 and 77 K, respectively was measured. The sheet carrier concentration in the channel did not change with x, and was nearly the same with an average value of 1.5×10 12/cm 2. A narrow photoluminescence linewidth of 15 meV was measured indicating the high quality of the epilayers. A red shift in the position of the PL peak energy from 0.86 to 0.76 eV was observed with an increase in x. A two-mode Raman characteristic was clearly seen with the two LO modes (InAs-like LO and GaAs-like LO) located at 226 and 268 cm −1, respectively. When the In mole fraction was increased in the channel, the InAs-like LO mode peak intensity increased while that of GaAs-like LO mode decreased. Correspondingly, the peak intensity ratio of InAs-like LO mode and GaAs-like LO mode increased from 0.78 to 1.10.