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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 Cd_yZn_1−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, In_xGa_1−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 Cd_yZn_1−ySe/ In_xGa_1−xAs heterostructures grown by molecular beam epitaxy (MBE) on GaAs(001) wafers. In_xGa_1−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) Cd_yZn_1−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.