Pulsed Laser Deposition of Bi- And Sb-based Solid Solutions and Multilayer Structures
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Pulsed Laser Deposition of Bi- And Sb-based Solid Solutions and Multilayer Structures Arik G. Alexanian, Hovsep N. Avetisyan1, Karapet E. Avjyan, Nikolay S. Aramyan, Garegin A. Aleksanyan, Romen P. Grigoryan2, Ashot M. Khachatryan, and Arsham S. Yeremyan Department of Semiconductor Electronics, Institute of Radiophysics & Electronics of National Acad. Sci. of Armenia, 1 Brs. Alikhanyan st., 378410, Ashtarak, Armenia 1 Institute for Physical Research of National Acad. Sci. of Armenia, 378410, Ashtarak, Armenia 2 Yerevan Physics Institute, 2 Brs. Alikhanyan st., 375036, Yerevan, Armenia ABSTRACT Thin films of Bi, Sb, solid solutions Bi1-xSbx, as well as multilayer structures Bi-Sb-Bi-Sb-from elementary sources were produced by pulsed laser deposition for optoelectronic applications. KBr crystals were used as substrates. The solid solutions Bi1-xSbx were obtained by co-evaporation of single targets of Bi and Sb. Structural investigations show that the performance of produced films depends on both the amount of material deposited per pulse of laser energy and the ratio of this amount for bismuth and antimony. Based on this the technological regimes of growth temperature and laser intensity ranges were determined in which single-crystalline growth of films with certain x is possible. Single-crystalline films of Bi1xSbx were obtained in the range of x (0.12—0.48), which corresponds to semiconductor state of this solution. The method of sequential deposition is used for fabrication of multilayer structures Bi/Sb with quantum-confined layers of bismuth. The growth regime with practically excluded interdiffusion of materials is found. Results of spectral investigations are shown to be in agreement with the theoretically predicted semimetal-to-semiconductor transition of bismuth as a result of quantum confinement. INTRODUCTION Advances of current technologies enlivened recently the investigations of thin-film bismuth, antim ony, solid solutions Bi1-xSbx, as well as multilayer structures Bi-Sb-Bi-Sb--- [1,2]. The small effective masses and high mobility in these materials make them suitable for observation of quantum-confinement effects. The interest to semiconductor solid solutions Bi1-xSbx (0,08 ≤ x ≤ 0,22) is still large due to their use as materials for sub-millimeter wavelength detectors, lasers [3], as well as for thermoelectric elements with improved characteristics. On the other hand, the fabrication of multilayer structures Bi/Sb with dimensionally quantized layers of bismuth, where the semimetal-to semiconductor (SM-SC) transition is possible, would allow one to use these structures for generation and reception of IR radiation [4]. In this respect, it is necessary to obtain a sharp profile of the confining potential, which would lead to effective localization of carriers in the structure. Therefore, an important problem is the development of technology for fabrication of structures consisting of single-crystalline layers of Bi and Sb in the regime, where the interdiffusion of materials is practically excluded
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