Photothermal ionisation spectroscopy of oxygen-related shallow defects in crystalline silicon (original) (raw)
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Characterisation of oxygen and oxygen-related defects in highly- and lowly-doped silicon
Materials Science and Engineering B, 2003
In this paper, an overview will be given about analytical techniques which are suitable for the study of oxygen and oxygen precipitation in highly-and lowly-doped silicon. It will be shown that in the case of highly-doped silicon, the application of Fourier Transform Infrared (FT-IR) absorption spectroscopy requires the use of ultra-thinned or high-fluence irradiated samples and a dedicated data analysis. This sample preparation is necessary to reduce the free carrier absorption in the mid-IR region. It is shown that besides the interstitial oxygen concentration [O i ] and the amount of precipitated oxygen, it is possible to determine the stoichiometry of oxygen precipitates from the study of the corresponding absorption bands. Oxygen precipitation in p ' silicon can also be investigated by the D1 Á/D2 lines in photoluminescence (PL) on as-grown or heat Á/treated material without special sample preparation. In oxygen-doped high-resistivity float-zone silicon, standard FT-IR analysis can be applied to determine [O i ]. The presence of oxygen-related shallow donors can be probed by a combination of electrical (spreading resistance probe, SRP; capacitance Á/voltage, C Á/V ) and (quasi-)spectroscopic techniques (deep-level transient spectroscopy, DLTS). #
Oxygen Related Lattice Defects in Silicon: Present Status
MRS Proceedings, 1992
The structural characterization of the oxygen related lattice defects formed under different thermal cycling conditions is discussed. The present understanding on the nature of rod-like defects and oxide precipitates is reviewed. Attention is given to the whole lattice defect spectrum which is induced by the oxygen precipitation. The influence of carbon and dopants on the defects is discussed.
The role of silicon interstitials in the formation of boron-oxygen defects in crystalline silicon
2005
Oxygen-rich crystalline silicon materials doped with boron are plagued by the presence of a well-known carrier-induced defect, usually triggered by illumination. Despite its importance in photovoltaic materials, the chemical make-up of the defect remains unclear. In this paper we examine whether the presence of excess silicon self-interstitials, introduced by ion-implantation, affects the formation of the defects under illumination. The results reveal that there is no discernible change in the carrier-induced defect concentration, although there is evidence for other defects caused by interactions between interstitials and oxygen. The insensitivity of the carrier-induced defect formation to the presence of silicon interstitials suggests that neither interstitials themselves, nor species heavily affected by their presence (such as interstitial boron), are likely to be involved in the defect structure, consistent with recent theoretical modelling.
What Do We Know about Hydrogen-Induced Thermal Donors in Silicon?
Journal of The Electrochemical Society, 2009
The hydrogen-plasma-accelerated formation of shallow thermal donors in silicon has been studied for a wide range of doping concentration and interstitial oxygen content ͓O i ͔ by electrical and spectroscopic techniques. The plasma-hydrogenated material has been heat treated for different times in the temperature range of 275-500°C. It is shown that, besides oxygen thermal donors ͑OTDs͒, hydrogen-related shallow thermal donors ͑STDHs͒ also play a crucial role in the hydrogen-assisted creation of excess carriers. The impact of different factors on the introduction rate of the shallow donors will be discussed, whereby a strong role is played by the doping concentration and type ͑i.e., the Fermi-level position during the thermal anneal in air͒. Generally, shallow donor formation is faster in p-compared to n-type Si, which is associated with the different charge state of H. From combined deep-level transient spectroscopy and Fourier transform infrared absorption spectroscopy, it is concluded that the additional free carriers are contributed by both STDH and OTD centers, so that H not only plays a catalytic role but actively takes part in the donor formation, depending on the experimental conditions. Finally, from our data some conclusions can be made regarding the nature of the STDHs, which is still a matter of debate.
Journal of Applied Physics, 2021
It is well established that boron reacts with two oxygen atoms in Czochralski-grown silicon (Cz-Si) to form a defect, which is responsible for the dominant light-induced degradation (LID) in solar cells made from Cz-Si:B material. The detrimental effect of LID has stimulated a move by solar cell manufacturers to the use of silicon with other group-III dopants, particularly with gallium. Cz-Si:Ga is immune to the BO-type LID. The information available in the literature on the interactions of oxygen with either Al, Ga, or In impurities in Si is limited. We use ab initio modeling and junction spectroscopy techniques to study a family of defects with unusual electronic properties, which have been detected in Cz-Si samples doped with different shallow acceptor species. We have carried out detailed measurements of the temperature dependencies of hole emission rate, equilibrium occupancy, and hole capture kinetics for the traps observed in differently doped p-type Cz-Si samples. It is found from the analysis of the changes in magnitude of the deep-level-transient signals with temperature that the equilibrium occupancy function of the traps is characteristic for a defect with negative-U properties in all the samples. The positions of the E(−/+) occupancy level of the defects are very close in differently doped samples, E(−/+) = E v + (0.31 ± 0.01) eV. It is argued that the oxygen dimer interacts with group-III atoms in silicon and these interactions result in the formation of A s O 2 complexes (A is either B, Al, Ga, or In atom) with very similar electronic properties.
Behaviour of oxygen in CZ-silicon during 430–630°C heat treatment
Materials Science and Engineering: B, 1998
The generation of thermal donors (TDs) depends on initial oxygen concentration, annealing temperature and its duration. An annealing process at 450°C for several hours generates upto : 10 16 cm − 3 TDs. We found that maximum concentration of TDs formed at 480°C was :1.0× 10 15 cm − 3 which reduces to a minimum of :2.6× 10 14 cm − 3 at 510°C suggesting thereby that the TDs got annihilated in this temperature range. The number of TDs now increases with a corresponding increase in annealing time giving birth to new donors (NDs). Activation energy for oxygen diffusion was found to be 0.6 9 0.1 eV and of silicon self interstitials : 0.4 eV. Therefore, it is quite logical to conclude that oxygen diffusion at low temperatures depends on the transport of the self interstitials which are chiefly due to the formation of molecule-like oxygen clusters. This confirms the formation and diffusion of molecule-like oxygen clusters in silicon at low temperatures.
Journal of Applied Physics, 2018
It has been recently suggested that oxygen-related bistable thermal double donors (BTDDs) are responsible for the reduction of minority carrier lifetime and conversion efficiency of novel amorphous-crystalline Si heterojunction solar cells with their base formed from n-type Czochralski-grown (Cz) silicon [M. Tomassini et al., J. Appl. Phys. 119, 084508 (2016)]. To test this hypothesis, we have studied processes associated with carrier emission and capture by BTDDs in p +-n and Schottky barrier diodes on n-type Cz-Si materials with the use of junction capacitance techniques. By means of deep level transient spectroscopy, we have detected electron emission signals from the deep donor state of the BTDD-0 and BTDD-1 centers. The values of activation energy for electron emission (E em) have been determined as 1.01 ± 0.01 and 0.91 ± 0.01 eV for the BTDD-0 and BTDD-1 centers, respectively. Such high E em values are very unusual for defects in Si. We have carried out measurements of electron capture kinetics and associated shallow donor-deep donor transformations for the BTDD-0 and BTDD-1 defects at different temperatures in the diodes with different doping levels. Energy barriers for the capture-transformation processes have been determined. It is argued that BTDDs are responsible for carrier trapping in n-type Cz-Si crystals but are not effective recombination centers.
Influence of oxygen and carbon on the generation and annihilation of radiation defects in silicon
Materials Science and Engineering: B, 1996
The influence of oxygen and carbon on the generation and annihilation of radiation defects in silicon is studied by deep level transient spectroscopy (DLTS), correlated with photoluminescence (PL) analyses. N+p silicon diodes with interstitial oxygen content between 10 ~(' cm ~ and l0 ts cm 3 and carbon content below 101~ cm 3, are irradiated by 2 MeV electrons with fluences ranging from 5 x l0 t4 cm 2 to 10 I~ cm 2. The DLTS spectra reveal two hole traps characterised by an activation energy of respectively 0.19 eV and 0.36 eV. Correlation with PL measurements confirmed the association of the 0.36 eV level with a C~O~ and/or CiC~ complex. Isothermal anneals performed at 200 °C resulted in a gradual conversion of the E, +0.19 eV to a defect level at E,. +0.24 eV. From the oxygen content dependence of the transformation it is suggested that the divacancy diffuses and is trapped by interstitial oxygen forming a V20 complex. Kc:vwords: Oxygen: Carbon: Silicon 0921-5107/96/$15.00 ~: 1996 Elsevier Science S.A. All rights reserved SSDI 0921-5107(95)01269-9
Materials Science and Engineering B Advanced Functional Solid State Materials, 2000
The hydrogen-enhanced thermal donor (TD) formation in Czochralski (Cz) silicon is used for the characterization of the interstitial oxygen distribution by spreading resistance probe (SRP) analysis or by the carrier concentration from capacitancevoltage (C-V) measurements. For as-grown wafers or wafers with a denuded zone, the enhanced TD formation in Cz silicon has been studied by applying a hydrogenation from a plasma. A kinetic model for the hydrogen-enhanced TD formation is presented, and a method for the conversion of the carrier concentration due to TDs into a concentration of interstitial oxygen is proposed. For comparison, infrared spectrometry was applied for the characterization of the oxygen concentration in the samples. On the basis of the proposed model, the analysis by the SRP or C-V measurements of Cz Si samples containing TDs, which were generated with the support of hydrogen, can be used for the quantitative estimation of the distribution of interstitial oxygen in the as-grown wafers as well as, at least qualitatively, of the interstitial oxygen distribution in wafers with denuded zones. : S 0 9 2 1 -5 1 0 7 ( 9 9 ) 0 0 4 4 7 -X