InP/InxGa1-xAs (0.53 ≤ x ≤ 0.81) high electron mobility transistor structures grown by solid source molecular beam epitaxy

The effect of varying Tn mole fraction from x = 0.53-0.81 in InxGa1-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 x 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 I. 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. (C) 1999 Elsevier Science B.V. All rights reserved.