Thin InAs membranes and GaSb buffer layers on GaAs(001) substrates
(Color online) (a) Schematic illustration of a GaSb buffer layer grown on a GaAs(001) substrate. Structural and electrical quality of GaSb buffer layers as a function of (b) V/III ratio, (c) temperature during buffer growth, and (d) temperature during nucleation. The growth temperature (TG ), nucleation temperature (T nucl), and V/III ratio were set to optimized values in each series.
(Color online) (a) 2θ–ω scans around the 004 reflection of InAs/GaSb structures with various GaSb thicknesses. The thickness of the InAs layer is 23 nm for all samples. Pendellösung fringes are observed for the InAs peak at larger buffer thicknesses. The vertical line indicates the position of fully strained InAs. (b) Structural and electrical properties of InAs/GaSb as a function of the GaSb layer thickness. The quality of the InAs layer is directly related to the GaSb buffer layer and the quality of the GaSb layer increases with the thickness.
(Color online) 4 × 4 μm2 AFM images of (a) 300 nm optimized GaSb buffer layer, (b) InAs surface, grown on 1.3 μm GaSb buffer. The screw dislocations are clearly visible on the GaSb surface, while the InAs growth starts to mitigate them. Insets show schematic illustrations of the evaluated structures. The rms values are 4.35 and 5.93 nm for (a) and (b), respectively.
(Color online) (a) SEM image of under-etched membrane for Hall measurements. (b) Hall mobility and resistivity of under-etched InAs membranes. The inset shows the Hall voltage change with magnetic field for the 23-nm-thick membrane. The current is set to 1 μA.
Root-mean-square values of GaSb buffer layers.
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