Journal of Crystal Growth 237–239 (2002) 227–233 Nanostructures formation and optical properties of II–VI semiconductor compounds H. Mariette*, L. Marsal, L. Besombes, F. Tinjod, B. Gilles, K. Kheng, J.L. Rouvi " ere CEA-CNRS group ‘‘Microstructures de Semiconducteurs II-IV’’, Laboratoire de Spectrom! etrie Physique, Universit ! e J. Fourier-Grenoble I, and D! epartement de Recherche Fondamentale sur la Mati " ere Condens ! ee/SP2M, 17 Avenue des Martyrs, 38054 Grenoble cedex 9, France Abstract Self-assembled CdTe quantum dots made on ZnTe buffer have been obtained in special growth conditions: the dot- like islands form themselves in a metastable zone which occurs just before the onset of the plastic relaxation transition. This was evidenced by comparing the in situ in-plane relaxation and structural data for two growth processes, the conventional molecular beam epitaxy (MBE), and the atomic layer epitaxy (ALE). These results demonstrate the importance of the kinetic effect on the formation of CdTe nanostructures. The kinetics during growth, studied here by comparing MBE and ALE processes, not only delays the onset of the plastic relaxation by revealing an intermediate zone where the islands can be formed, but also allows some interdiffusion between the cations Cd and Te to occur, as evidenced by studying the optical and structural properties of these dot-like islands. r 2002 Elsevier Science B.V. All rights reserved. PACS: 78.66.Hf.; 71.55.Gs; 68.55.a Keywords: A3. Atomic layer epitaxy; B2. Semiconducting II–VI materials 1. Introduction Some combinations of lattice-mismatched semi- conductors can exhibit, under specific epitaxial growthconditions,asharptransitionfromalayer- by-layer 2D growth to the formation of 3D islands. This Stranski–Krastanow (SK) growth mode allows the relaxation of highly strained 2D layers through the free surfaces of 3D islands instead of generating misfit dislocations [1] (for a recent review, see Ref. [2]). These islands are expectedtobedislocation-freeandarethusofhigh structural quality. Usually, their typical sizes are onthescaleofafewnanometers,sothattheseself- assembled quantum dots (QDs) are attractive nanostructures for both fundamental physics (interplays of quantum confinement effects, Cou- lomb blockade effects, etc.) and device applica- tions (QD lasers with higher gain, temperature- insensitive laser threshold, etc.) [2]. Most of the work concerning self-assembled QDs has been done on III–V materials such as InAs/GaAs [3] and IV–IV materials such as Si/Ge [4] for which the SK growth mode has been well *Corresponding author. Tel.: +438-7856-88; fax: +438- 7851-97. E-mail address: hmariette@cea.fr (H. Mariette). 0022-0248/02/$-see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0022-0248(01)01911-X