Surface morphology of a series of growths on a 6-in., on-axis GaAs substrate: 5 × 5 μm2 AFM images of (a) single-step GaSb M-buffer (300 Å nucleation layer plus 1 μm GaSb); (b) an additional 3 μm of GaSb (image enhanced to highlight the monolayer steps surrounding the dislocation at the center of the mounds); (c) and the full λc ∼ 4 μm nBn photodetector structure; (d) the Nomarski contrast microscope image of the full nBn.
(004) HRXRD spectra from the growths on 6-in., on-axis GaAs substrate of (a) a single-step 1 μm thick GaSb M-buffer with a AlAsSb/AlAsSb SC-SLS layer, capped with 3 μm of GaSb; and (b) the addition of the full λc∼ 4 μm nBn photodetector structure.
XTEM images of a full nBn grown on a single-step GaSb M-buffer with a AlAsSb/AlAsSb TS-SLS dislocation filtering layer, grown on a 6-in., on-axis GaAs substrate: the full epilayer stack on the right; close-ups on the left of the epi-substrate interface (bottom), dislocation propagation through and annihilated within the SLS (middle), and the nBn active layers demonstrating a clear absorber/barrier interface (top).
Surface and structural characteristics from a series of growths on a 6-in., 2° miscut GaAs substate: 5 × 5 μm2 AFM images of (a) the graded GaAsSb M-buffer, clearly showing the crosshatched morphology; (b) an additional 3 μm of GaSb; (c) the full λc ∼ 4 μm nBn photodetector structure; (d) XTEM image for the same epiwafer showing the full layer stack; and (e)Nomarski microscope image of the full nBn epiwafer surface.
Excellent structural and optical uniformity of a full nBn detector grown on 6-in. GaAs: (a) 5-point HRXRD spectra; (c) 12-point 77 K PL peak λ and FWHM; (b) diagram depicting the orientation of the measurement steps across the wafer relative to its position in the substrate holder for MBE growth.
(a) 150 K PL spectra of a nBn photodetector structure grown on 4-in. GaSb substrate, and on 6-in. GaAs substrates using various M-buffers, where Buffer  was single-step GaSb, [2a] was GaSb with the SC-SLS, [2b] used the TS-SLS, and  was the graded GaAsSb buffer; (b) sample J-V curves from the nBn grown on the single-step GaSb M-buffer with TS-SLS.
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