CHARACTERISTICS OF INXGA1-XAS GAAS PSEUDOMORPHIC MODULATION-DOPED FIELD-EFFECT TRANSISTOR/

High performance pseudomorphic InxGa1-xAs/GaAs modulation doped field effect transistors (MODFETs) grown by metalorganic chemical vapor depo sition have been characterized at dc using modulation spectroscopy, A transconductance as high as 175 and 253 mS/mm was obtained at 30% and 40% indium content, respectively. In order to identify the origin of t he MODFETs' features we have performed a self-consistent Schrodinger-P oisson calculation of the subband and intersubband energies. The photo reflectance spectra can be divided into two parts by the photon energy ; one belongs to the GaAs bulk transition and the other belongs to the InxGa1-xAs/GaAs quantum well transition including two-dimensional ele ctron gas (2DEG) signals. The built-in electric fields are 20.6 x 10(4 ) V/cm and 22.6 x 10(4) V/cm. From photoreflectance spectra peaks at 1 .035 and 1.06 eV show that their energies agree with line shape fittin g and 2DEG theory. (C) 1997 American Institute of Physics.