Effect of parameters of Ge(Si)/Si(001) self-assembled islands on their electroluminescence at room temperature
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TRONIC AND OPTICAL PROPERTIES OF SEMICONDUCTORS
Effect of Parameters of Ge(Si)/Si(001) Self-Assembled Islands on their Electroluminescence at Room Temperature D. N. Lobanova^, A. V. Novikova, K. E. Kudryavtseva, D. V. Shengurova, Yu. N. Drozdova, A. N. Yablonskiya, V. B. Shmagina, Z. F. Krasilnika, N. D. Zakharovb, and P. Wernerb aInstitute
of Physics of Microstructures, Russian Academy of Sciences, Nizhni Novgorod, 603950 Russia ^e-mail: [email protected] bMax-Planck-Institute für Mikrostrukturphysik, Halle/Saale, 06120 Germany Submitted June 2, 2008; accepted for publication June 20, 2008
Abstract—The electroluminescence (EL) of multilayered p–i–n structures with the self-assembled Ge(Si)/Si(001) islands are investigated. It is found that the structures with islands grown at 600°C have the highest intensity of the electroluminescence signal at room temperature in the wavelength range of 1.3–1.55 µm. The annealing of structures with the Ge(Si) islands leads to an increase in the EL-signal intensity at low temperatures and hampers the temperature stability of this signal, which is related to the additional Si diffusion into islands during annealing. The found considerable increase in the electroluminescence-signal intensity with the thickness of the separating Si layer is associated with a decrease in the elastic stresses in the structure with an increase in this layer’s thickness. The highest EL quantum efficiency in the wavelength range of 1.3–1.55 µm obtained in investigated structures amounted to 0.01% at room temperature. PACS numbers: 73.40.Lq, 78.55.-m, 78.60.Fi, 78.67.Hc DOI: 10.1134/S1063782609030105
1. INTRODUCTION A major problem in manufacturing the light-emitting structures on the basis of silicon is its low quantum efficiency of the radiative recombination of charge carriers. Nowadays it is possible to single out two methods for increasing the radiative-recombination efficiency in the structures on the basis of silicon. The first method is based on improvement of the quality of structures by decreasing the concentration of nonradiative-recombination centers for the charge carriers in them [1], and the second is the spatial localization of charge carriers in a small structure region [2, 3]. In structures with Ge(Si) self-assembled islands, it is possible to use both these ways due to the localization of charge carriers in defect-free islands [4, 5]. An important feature of devices based on the structures with Ge(Si) islands is also the possibility of their operation in the wavelength range of 1.3–1.55 µm inherent for the current opticalfiber communication lines. Bulk silicon in this wavelength range is transparent, which makes it possible to use waveguides on its basis and opens new avenues for the integration of optical and electronic components on one silicon substrate. In the last few years, various teams [6–9] reported on successes in observing the electroluminescence (EL) at room temperature from structures with Ge(Si) islands. The best results in the region of formation of light-emitting dio
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