MBE growth of high quality metamorphic HEMT structures on GaAs

Metamorphic high electron mobility transistor (MHEMT) structures with In_0.53Ga_0.47As channels were grown by molecular beam epitaxy on GaAs substrates using As-, P-, and Sb-based buffer layers. Structural, electrical, and optical characterizations were used to correlate buffer layer design and growth parameters with channel carrier mobility, surface morphology, and photoluminescence efficiency. X-ray reciprocal maps indicate complete lattice relaxation of buffer layer. All MHEMTs studied in this work exhibited excellent transport properties comparable to HEMTs grown lattice-matched on InP. RMS roughness of <14 Å were achieved for both InAlGaAs and AlGaAsSb-based buffers. MHEMT devices with 0.15 μm gates were fabricated successfully on As-based M-buffers with transconductance of ~700 mS/mm, saturated drain current at zero gate bias of 200 mA/mm, and gate-drain breakdown voltage of 6.6 V