(a) Nomarski micrograph of films grown on GaAs with and a top layer composition of . Vertical lines are FTs formed during growth with . SEM images of trenches on layers (b) from plan-view and (c) cross-sectional view. A depth of 100–300 nm is measured for these FTs.
(a) Nomarski micrograph of a graded buffer grown on GaAs with , , and top layer composition of . (b) AFM micrograph showing surface RMS roughness of 2.45 nm.
Threading dislocations observed by (a) PVTEM and (b) CL on tensile-strained buffers. Both PVTEM and CL comfirmed a TDD of for .
(a) XTEM micrograph of a microtwin found below all FTs. (b) PVTEM of FT showing dislocation pileups caused by FTs.
Nomarski micrographs of graded buffers with a top layer composition of , , and of (a) 4% and (b) 2%. decreased from to by halving .
(a) Nomarski and (b) AFM micrographs of a compressively-strained buffer with a top layer composition of with . A smooth morphology, with no FTs was observed, and a surface RMS roughness of was extracted from AFM.
(a) PVTEM , and (b) CL micrographs of compressively-strained buffers. The PVTEM survey showed while the CL showed .
Normalized room temperature PL of metamorphic films grown on with different In compositions.
XTEM of a lattice-matched layer on top of on GaAs. Threading dislocations are not formed at the interface. Insets at right show selected area diffraction patterns of the layer along both  and and show no evidence of CuPt ordering.
(a) L-IV characteristics under approximate AM1.5G illumination and (b) EQE measurements of solar cells with 39% (—), 43% (– –), and 48% (- - -) In content. trends up with decreasing In content. Inset of (a) depicts solar cell growth structure.
Summary of solar cell device characteristics.
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