Radiative recombination processes of thermal donors in silicon

Abstract

There is a recent, renewed attention on the possible development of optical emitters compatible with silicon microelectronic technology and it has been recently shown that light emitting diodes could be manufactured on dislocated silicon, where dislocations were generated by plastic deformation or ion implantation. Among other potential sources of room temperature light emission, compatible with standard silicon-based ULSI technology, we have studied old thermal donors (OTD), as the origin of their luminescence is still matter of controversy and demands further investigation.In this work we discuss the results of a spectroscopical study of OTD using photoluminescence (PL) and Deep Level Transient Spectroscopy (DLTS) on standard Czochralsky (Cz) silicon samples and on carbon-doped samples. We were able to show that their main optical activity, which consists of a narrow band at 0.767 eV ( P line), is correlated to a transition from a shallow donor level of OTD to a deep level at Ev+0.37 eV which is tentatively associated to C-O complexes. As we have shown that the P line emission persists at room temperature, we discuss about its potentialities to silicon in optoelectronic applications.

Study of the correlation between radiative and non-radiative recombination channels in silicon

“…In order to evaluate the relative influence of these two traps on the recombination processes, and thus on the lifetime, we have compared in figure 5 the evolution with the annealing time of the lifetime and of the reciprocal of the intensity of the P line at 0.767 eV, which is always present in the PL spectra (see figure 6) in the presence of thermal donors [12].…”

“…Finally, the parameters of the deep levels associated with majority carrier traps were obtained from the results of our previous work [12], where standard DLTS and minority carrier transient spectroscopy (MCTS) measurements were carried out by means of a SULA Tech. Inc. instrumentation.…”

“…In this work, the case of thermal donors was chosen as an example of a system where the properties of the centres responsible for the radiative and non-radiative recombination processes and the evolution with the annealing time of their concentration are already known from photoluminescence (PL) and deep-level transient spectroscopy (DLTS) measurements [12]. The injection conditions were determined by comparing the calculated concentration of excess free carriers (δp) and the equilibrium majority carrier concentration (n 0 ).…”

Effect of high pressure isostatic annealing on oxygen segregation in Czochralski silicon

“…Considering that we have already shown that the intensity dependence of the P line on the treatment time follows that of the NL8 center [15][16][17][18] we might conclude that the concentration of this center is not affected by the applied pressure, while that of the other donors is. Considering that we have already shown that the intensity dependence of the P line on the treatment time follows that of the NL8 center [15][16][17][18] we might conclude that the concentration of this center is not affected by the applied pressure, while that of the other donors is.…”

“…The overall concentration of these donors, which depends on the temperature, on the annealing time, and on the initial oxygen content, as well as on their double donor nature, could be determined by Hall effect measurements. 15,16 For this reason, we consider the presence of the P line in the PL spectrum as the fingerprint of a specific center generated during the thermal annealing at 450°C, which is, in fact, present in all the samples examined, as it shown in Fig. For one of these donor centres, the NL8 one, whose electronic structure is known from electron paramagnetic resonance and electron-nuclear double resonance measurements, 14 a correlation was found between the PL intensity in the excitonic range and the intensity of a PL line at 0.767 eV, known as the P line and the annealing time at 450°C.…”