Luminescence of isoelectronically ion‐implanted SiO₂ layers

Abstract

Scanning electron microscopy (SEM) and cathodoluminescence (CL) in combination with scanning transmission electron microscopy (STEM) have been used to investigate thermally grown amorphous silicon dioxide layers implanted isoelectronically with group IV ions (C+, Si+, Ge+, Sn+, Pb+) as well as with group VI ions (O+, S+, Se+). Besides the main luminescent centers in a‐SiO2 layers: the red R luminescence (650 nm; 1.9 eV) of the non‐bridging oxygen hole centers (NBOHC), the blue B (460 nm; 2.7 eV) and the UV (290 nm; 4.3 eV) band of the oxygen deficient centers (ODC), in ion implanted silica additional emission bands are observed. E.g. in Ge+ implanted layers a huge violet band appears at 410 nm (3.1 eV) increasing with the thermal annealing process due to formation of Ge dimers, trimers or higher aggregates, finally leading to destruction of the luminescence centers by further growing to Ge nanoclusters. The Ge cluster size is shown by STEM cross section micrographs. Generally, group IV element implantation and partial substitution of silicon increases the luminescence in the blue/violet region whereas group VI elements and additional oxygen increase the intensity in the red region, confirming the association of the blue and the red luminescence with oxygen deficient centers and oxygen excess centers, respectively. Thus, the cathodoluminescence spectra of sulfur and oxygen implanted SiO2 layers under special conditions show besides the characteristic luminescence bands a multimodal structure beginning in the green region at 500 nm and extending up to the near infrared region at 820 nm. The energy step differences of the sublevels amount in the average 120 meV and indicate vibronic‐electronic transitions, probably of O2– interstitial molecules. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Layer dependence of the electronic band alignment of few-layer MoS2 on SiO2 measured using photoemission electron microscopy

“…From photoluminescence studies, oxygen deficiency centers (ODCs) 73 have been shown to produce emission bands 4.3 eV above the valence band of SiO 2 . 74,75,76,77 Defects in SiO 2 are also observed in the DUV photoemission spectra of glassy SiO 2 and quartz implanted with metals ions. 78,79 In Fig.…”

Thermal decomposition and new luminescence bands in wet, dry, and additional oxygen implanted silica layers

“…The latter one often appears in ion-implanted layers, e.g. Ge + , Sn + , and S + [23] and was attributed to twofold co-ordinated implantation species, but in the present paper it appears as an intrinsic silica decomposition defect associated most probably by OH groups or even dissociated oxygen. As far as we may exclude hydrogen for UV-V luminescence promotion, see [22], oxygen remains as the decisive species for that short wavelength luminescence.…”

“…In previous work we did investigate ion-implanted SiO 2 layers: Si + , O + , Ge + in [18]; H + [22], as well as isoelectronic substitutions: S + , Se + for oxygen and C + , Ge + , Sn + , Pb + for silicon [23]. There we applied a post-implantation thermal annealing up to T a = 1100°C and have obtained maximum luminescence for annealing temperatures T a = 80-900°C, i.e.…”

Ion implantation, luminescence, and cluster growth in silica layers

“…A closer look in Ref. [12] shows a crystalline structure (lattice) pattern of germanium nanoparticles clearly distinguishable from the amorphous host matrix. The nanocluster sizes are growing with annealing temperature from 1 to 7 nm at T a = 900°C to 3-12 nm at T a = 1100°C as shown in Fig.…”

“…These two bands have been attributed to singletsinglet and triplet-singlet transitions, respectively, in isoelectronically twofold coordinated silicon (@Si ÅÅ ), germanium (@Ge ÅÅ ), and tin (@Sn ÅÅ ) [7,10]. A strong violet luminescence band at 3.1 eV is often reported in Ge doped silica and attributed to the Ge-related oxygen deficient center Ge-ODC [9] or low-dimensional Ge nanoclusters imbedded in the silica matrix, [11,12].…”