1063-7826/04/3805- $26.00 © 2004 MAIK “Nauka/Interperiodica” 0550 Semiconductors, Vol. 38, No. 5, 2004, pp. 550–553. Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 5, 2004, pp. 570–573. Original Russian Text Copyright © 2004 by Sachenko, Gorban’, Kostylyov. 1. INTRODUCTION In view of the possibility of fabricating large-scale silicon integrated circuits including optical transmis- sion lines, much attention has been paid in recent years to electroluminescence in silicon barrier structures at room temperature (see, for example, [1–3]). Both device structures used for the photoelectric conversion of solar energy [1] and silicon diodes [2, 3] were stud- ied. Specifically, an internal quantum yield of band- edge emission of ~1% was obtained in [1, 2]. It was shown in [3] that the band-edge electroluminescence (at least, at low temperatures) may be due to the annihi- lation of free excitons. The influence of excitons on the effective lifetime of electron–hole pairs, band-edge photoluminescence, current–voltage characteristics, and the ultimate effi- ciency of photoelectric conversion in pure silicon and silicon device structures at room temperature was stud- ied in [4–9]. When carrying out the analysis, we assumed that two interrelated subsystems (electron– hole and exciton) exist in a semiconductor and a quasi- equilibrium between these subsystems is maintained due to the coupling of electron–hole pairs into excitons and the decay of excitons into electron–hole pairs. In this approach, it was shown that the effective lifetime of electron–hole pairs in a number of practically impor- tant cases may be controlled by nonradiative exciton Auger recombination involving deep centers; the inter- nal quantum yield of band-edge photoluminescence may be as high as 15% in this case. In this study, on the basis of the results of [4–6], we performed a detailed analysis of the conditions under which the highest quantum yield of band-edge electroluminescence can be obtained in Si p–n and p–i–n barrier structures. Spe- cific quantitative estimations are made for the room temperature region. 2. BAND-EDGE ELECTROLUMINESCENCE IN FORWARD-BIASED SILICON DIODES Let us consider the situation when the thicknesses of the n- and p-type regions of a diode exceed the diffu- sion lengths of electrons and holes in these regions. In this case, we can exclude the effect of surface recombi- nation. We will also assume that the excitation is linear; i.e., the inequalities n n  p n exp(qV/kT) and p p  n p exp(qV/kT) are satisfied. Here, n n and p p are the con- centrations of majority carriers in the n- and p-type regions, respectively; p n and n p are the concentrations of minority carriers in the n- and p-type regions, respec- tively; q is the elementary charge; k is the Boltzmann constant; T is temperature; and V is the applied bias voltage. The diffusion-current density in such a diode is given by the conventional expression (1) where L p and L n are the diffusion lengths of minority carriers in the n- and p-regions, respectively, and D p and D n are the diffusivities of minority carriers in the n- and p-regions, respectively. In the case of linear excitation, the expressions for L p and L n can be written as [4, 5] (2) J q D p p n L p ------------ D n n p L n ----------- +     qV / kT ( 29 , exp = L p = D p 1 τ rp ------ A i 1 n * τ x ---------- +     n n C n C p + ( 29 n n 2 + + 1 –       1/2 , On the Ultimate Quantum Efficiency of Band-Edge Electroluminescence in Silicon Barrier Structures A. V. Sachenko, A. P. Gorban’, and V. P. Kostylyov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev, 03028 Ukraine e-mail: sach@isp.kiev.ua Submitted May 19, 2003; accepted for publication October 18, 2003 Abstract—The ultimate quantum efficiency of electroluminescence in silicon diodes and p–i–n structures at room temperature is calculated. It is shown that the internal quantum yield of electroluminescence is about 10% and is implemented at optimal doping levels for the n- and p-type regions of silicon diodes, ~10 15 and 5 × 10 16 cm –3 , respectively. With a decrease in the Shockley–Read–Hall lifetimes of electrons and holes, the inter- nal quantum yield of electroluminescence in silicon barrier structures drops. The physical processes related to the effect of excitons in silicon has much in common with those in electroluminescence, photoluminescence, and photoconversion. It is shown that only electroluminescent p–i–n structures are promising for use in silicon integrated circuits. © 2004 MAIK “Nauka/Interperiodica”. SEMICONDUCTOR STRUCTURES, INTERFACES, AND SURFACES