Münster 1997 – scientific programme
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HL: Halbleiterphysik
HL 13: Heterostrukturen
HL 13.4: Talk
Tuesday, March 18, 1997, 11:15–11:30, H1
Lattice matched InGaAs substrates for ZnCdSe active layers — •B.H. Müller1, L. Sorba1, R. Lantier1, S. Rubini1, S. Heun1, M. Lazzarino1, A. Franciosi1, and G. Salviati2 — 1Laboratorio Nationale TASC-INFM, Area di Ricerca, Padriciano 99, I-34012 Trieste, Italy — 2Istituto MASPEC del CNR, Parma, Italy
Most II-VI based blue-green lasers employ highly strained CdyZn1−ySe active layers. Strain has been shown to play a role in the propagation and multiplication of the defects responsible for early device degradation. In principle, InxGa1−xAs alloys represent possible lattice matched substrates for the growth of II-VI based blue-green lasers, but high quality wafers with x>0.04 are not available.
We investigated the structural quality of lattice matched CdyZn1−ySe/ InxGa1−xAs heterostructures grown by molecular beam epitaxy (MBE) on GaAs(001) wafers. InxGa1−xAs films with homogeneous composition x=0.18, and 0.27, and graded-composition layers in which x was varied from x=0 to 0.23 or 0.33 were fabricated for lattice match to blue (y=0.15) and green (y=0.25) CdyZn1−ySe emitters. Photoluminescence spectroscopy of 0.3-1.5µ m thick II-VI epilayers showed a reduction by orders of magnitude in the defect related emission as compared to relaxed layers grown on GaAs. Also transmission electron microscopy confirmed that the II-VI films no longer contain misfit dislocations. However, as observed by atomic force microscopy, the II-VI layers replicate the InGaAs buffer corrugation leading to a rms roughness in the 2-8nm range.