Effect of substrate orientation on phase separation in epitaxial GaInAsSb |
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Authors: | C A Wang D R Calawa C J Vineis |
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Affiliation: | (1) Lincoln Laboratory, Massachusetts Institute of Technology, 02420-9108 Lexington, MA |
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Abstract: | The effect of substrate misorientation on phase separation in Ga1−xInxAsySb1−y nominally lattice matched to GaSb is reported. The layers were grown at 575°C by organometallic vapor phase epitaxy on vicinal
(001) GaSb substrates, miscut
or (101). Ga1−xInxAsySb1−y (x ~ 0.1, ~ 0.09) layers, which have 300-K photoluminescence (PL) peak emission at ~2.1 μm, grow stepbunched and exhibit
minimal phase separation. The full width at half maximum of 4-K PL spectra is slightly smaller at 7 meV for layers grown on
substrates miscut toward
compared to 9 meV for layers grown on substrates miscut toward
and (101). Ga1−xInxAsySb1−y layers with higher alloy composition (0.16≤x≤0.19, 0.14≤y≤0.17), which have 300-K PL peak emission at ~2.4 μm, have significant
phase separation. These layers are characterized by increased lattice constant variations and epitaxial tilt, broad PL spectra
with significant band tailing, and strong contrast modulation in transmission electron microscopy. The degree of decomposition
depends on substrate miscut direction: Ga1−xInxAsySb1−y layers grown on (001)
substrates are more homogeneous than those grown on (001)
and (001)2°→(101) substrates. The results are attributed to the smaller adatom diffusion length on substrates miscut toward
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Keywords: | GaInAsSb phase separation substrate misorientation OMVPE |
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