MBE grown InAlAs/InGaAs lattice mismatched layers for HEMT application on GaAs substrate

Improved In0.45Al0.55As/In0.45Ga0.55As/In0.65Ga0.35As Inverse Composite Channel Metamorphic High Electron Mobility Transistor

“…The inverse stepgraded buffer structure provides a good relaxation of mismatch strain in the active layer. 7) The active layer consisted of a 15 nm undoped In 0:65 Ga 0:35 As channel layer, a 5 nm undoped In 0:45 Ga 0:55 As subchannel layer, a 5 nm undoped In 0:45 Al 0:55 As spacer layer, and a silicon planar doping layer. After a 25 nm undoped In 0:45 Al 0:55 As Schottky layer, a 20 nm Si-doped (1:5 Â 10 19 cm À3 ) In 0:45 Ga 0:55 As cap layer was finally grown.…”

“…The use of an inverse-step MM buffer allows reaching a high relaxation rate and achieving more reproducible and high values of electron mobility and saturated velocity. [7][8][9] Recently, several authors [10][11][12][13][14] have studied composite channels, in which they adopted a higher-''In''-content InGaAs channel near the side of the Schottky layer while using a lower-''In''-content InGaAs channel near the side of the buffer layer; breakdown voltage is enhanced due to the decrease in impact ionization. Nevertheless, due to the fact that electrons are located near the low-''In''-content channel, which is farther away from the gate under a more negative gate bias, the mobility and tranconductance decreased markedly.…”

Q-band low noise amplifiers using a 0.15μm MHEMT process for broadband communication and radio astronomy applications

“…The metamorphic buffer layer gradually varies the lattice constant from the GaAs substrate to that of the indium-rich active layer. The misfit dislocations can be trapped by using the buffer layer, and also prevent their propagation in the active layer grown on this buffer [3].…”

Low temperature step-graded InAlAs/GaAs metamorphic buffer layers grown by molecular beam epitaxy

“…Compositionally step-graded metamorphic layers, changing the composition of epilayers along the direction of epilayer growth step-by-step, have received considerable attention as buffer layers for large lattice mismatch epilayers on GaAs substrate [1]. This buffer can accommodate the large lattice mismatch between the active layer and the GaAs substrate by the formation of misfit dislocations, isolate these misfit dislocations and prevent their propagation into the active layer grown on the buffer [2][3][4]. It is widely used as buffer layer for microelectronic devices, such as metamorphic high electron mobility transistor (MM-HEMT) [5] and heterojunction bipolar transistors (HBT) [6].…”