Electron paramagnetic resonance of erbium doped silicon

Abstract

Electron paramagnetic resonance measurements have been made on samples of float zone silicon, implanted with 10 15 Er/cm 2 . One sample was coimplanted with oxygen to give an impurity concentration of 10 20 O/cm 3 and 10 19 Er/cm 3 . In this coimplanted sample, sharp lines are observed which are identified as arising from a single spin 1/2 Er 3ϩ center having a g tensor exhibiting monoclinic C 1h symmetry. The principal g values and tilt angle are g 1 ϭ0.80, g 2 ϭ5.45, g 3 ϭ12.60, and ϭ2.6°. In the absence of O, the sharp lines are not observed. No Er 3ϩ cubic centers were detected in either sample. Possible structures for the center are discussed. © 1996 American Institute of Physics. ͓S0003-6951͑96͒02051-7͔Rare-earth doped semiconductors have attracted a great deal of attention because of their possible applications in optoelectronics. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The sharp intra 4 f shell transitions, which result from the 4 f electrons being shielded from the full effect of the crystal field, give rise to emissions which are largely independent of the surrounding environment. These emissions can be electrically excited which is important for device applications. Erbium doped silicon has attracted particular attention because the Er 3ϩ transition 4 I 13/2 → 4 I 15/2 at 1.54 m matches the minimum in the absorption of silica-based optical fibers. One of the major problems hampering future applications of Si:Er in optoelectronics is the strong quenching behavior of both the photo 2 -and electroluminescence 1 on going from 77 K to room temperature ͑RT͒. It has now been shown that the incorporation of other impurities, notably oxygen, can significantly increase the luminescence intensity 2 and help to suppress the temperature quenching of the luminescence. 5 Recently 7-9 RT electroluminescence has also been obtained from Er-doped Si p-n diodes codoped with either O or F. Furthermore, it has been shown that, in spite of the low solid solubility 10 of Er in Si (ϳ2ϫ10 16 /cm 3 at 900°C͒ higher Er concentrations ͑up to ϳ10 20 /cm 3 ) can be incorporated by chemical vapor deposition, 11 molecular beam epitaxy, 12 or by using the solid phase epitaxial regrowth of an amorphous layer produced by Er implantation. 13 Codoping with O or F allows the suppression of Er segregation at the moving crystal-amorphous interface and the regrowth of thick (ϳ2 m͒ recrystallized layers. 14 All of these beneficial effects have been attributed 6 to modifications in the local environment of Er produced by the codopants. Although strong evidence of the modifications of the electrical properties of Er in Si in the presence of O ͑or F) has been provided, 4,15,16 there is little experimental information on how the site location and coordination of Er in Si is altered by the presence of other impurities.In this letter, we report on the first electron paramagnetic resonance ͑EPR͒ measurements made on Er implanted float zone ͑FZ͒ Si coimplanted with O. We show that the presence of oxygen has a pronounced effect on the type of E...

Electron spin resonance of Er–oxygen complexes in GaAs grown by metal organic chemical vapor deposition

“…It was reported that ESR lines from Er 3ϩ center with Er 2 O 3 structure were observed in a Si wafer implanted with Er and oxygen. 4 The ESR lines for the D center are observed in the same region of the magnetic field as the ESR lines observed in Si. It is known that Er 3ϩ ion occupies two different sites in Er 2 O 3 .…”

“…Knowledge of the microscopic structures of the rare earth impurities in semiconductor hosts is very important for fabricating efficient injection-type light emitting devices. To understand the microscopic structures, the electron spin resonance ͑ESR͒ measurements, [1][2][3][4][5][6][7] the extended x-ray absorption fine structure ͑EXAFS͒ measurements, 8,9 and the Rutherford backscattering ͑RBS͒ channeling measurements [10][11][12][13] have been performed on Er-doped GaAs, Er-doped Si, and Yb-doped InP.…”

Electron paramagnetic resonance and photoluminescence study of Er-impurity complexes in Si

“…Recently, we have reported a preliminary EPR study on Er-doped Si and indeed we have shown the presence of Er 3ϩ centers in Si. 19 In this paper we present the first detailed EPR study of Er complexes in Si implanted with Er together with either O or F. We show that the nature of the coimplanted ions as well as their concentrations and the postimplantation anneal treatments all affect the structure and/or the concentration of the Er complexes. The relationship between the EPR-active centers and the optically active centers is examined using high-resolution PL measurements.…”

“…At concentrations above the solubility limit, precipitation of Er into Er silicide will occur. Coimplantation with either O or F has been shown to help in suppressing precipitation and Er concentrations as high as of 1ϫ10 19 /cm 3 have been incorporated in a goodquality Si single crystal by ion implantation. 6,13 These beneficial effects have been attributed to modifications in the local environment of the Er atom through the formation of Er-impurity complexes.…”

Crystal field analysis of Dy and Tm implanted silicon for photonic and quantum technologies

“…Other RBS and PL measurements indicate that when annealed at over 800°C, 80% of Er occupies substitutional sites with tetrahedral symmetry [12]. Electron paramagnetic resonance (EPR) spectra of Er and O coimplanted Si indicate two Er 3+ centers having monoclinic C 1h symmetry [13] and trigonal symmetry [14]. The emission channelling technique indicates that Er in FZ Si occupies tetrahedral interstitial sites [15], and first-principles calculations indicate that the lowest energy configuration of Er in Si is Er 3+ at a tetrahedral interstitial site [16].…”