J.L. Lindström

Carbon-vacancy related defects in 4H- and 6H-SiC

Electron paramagnetic resonance (EPR) was used to study intrinsic defects in 4H- and 6H-SiC irradiated with 2.5 MeV electrons with doses ranging from 1×1017 to 2×1018 cm−2. In p-type 4H- and 6H-Si ...

Activation energies for the formation of oxygen clusters related to the thermal donors in silicon

Abstract The formation of different oxygen clusters related to the thermal donors (TDs) in Czochralski-Si giving rise to IR vibrational modes were investigated after annealing in the range 350–470 °C. Activation energies for the formation of clusters related to TDs ⩾ TD2 were estimated to be about 1.6–1.9 eV, according to previous investigations, while a lower value of about 1.25 eV was found for the formation of TD1-related clusters. The activation energy for the growth of pre-existing clusters with a band at 1012 cm −1 was estimated to be about 1.5 eV.

Deep luminescent centres in electron-irradiated 6H SiC

Abstract We report on our observation of several new photoluminescence (PL) spectra in electron-irradiated 6H SiC. In addition to the vacancy-related PL spectrum ranging from 1.36 to 1.44 eV, four other spectra with no-phonon lines in the regions of 0.9983–1.0738 eV, 1.0878–1.1342 eV and 1.3563–1.3711 eV were detected in 6H SiC. These luminescent centres are rather thermally stable. From the formation and annealing behaviour, these centres were suggested to be complexes, of which some involve a silicon vacancy.

Electron-paramagnetic-resonance studies of defects in electron-irradiated p-type 4H and 6H SiC

Abstract Defects in p-type 4H and 6H SiC irradiated by 2.5xa0MeV electrons were studied by electron paramagnetic resonance (EPR). Two anisotropic EPR spectra, labeled I and II, were observed in both 4H and 6H SiC. These spectra demonstrating triclinic symmetry of the center can be described by an effective electron spin S = 1 2 . The angle α between the direction of the principal g z of the g -tensors and the c -axis is determined as 63° and 50° for spectra I and II, respectively. In the 6H polytype, a third also similar EPR spectrum was detected. Based on their similarity in the electronic structure (electron spin, symmetry, g values), annealing behavior and temperature dependence, these spectra are suggested to be related to the same defect occupying different inequivalent lattice sites in 4H and 6H SiC. A pair between a silicon vacancy and an interstitial is a possible model for the defect.

Configuration transformation of metastable defects in 6H-SiC

The configuration transformation properties of two previously observed metastable defects in 6H-SiC have been studied using various junction space-charge techniques and simulation. The studied configuration transformation processes are mainly governed by the energy released during the electron capturing process. An electron capturing and configuration transformation model is suggested and a transformation probability between the configurations has been defined and measured. Finally, the obtained defect parameters and the configuration model were used to simulate the transformation behaviour.

Thermal donor formation in aluminum doped silicon

Abstract Aluminum as a dopant has been reported to enhance thermal donor (TD) formation in silicon. We present results based upon infrared (IR) studies of a recently discovered group of vibrational absorption bands related to the TDs. According to these vibrational absorption bands three categories of TDs has been suggested to develop in the temperature range 350–500 °C. Our results reveal that in comparison with dopants such as B and P the first category appearing is suppressed in Al-doped samples while the second category is not affected. The formation of the third category is enhanced in moderately (≈ 1 × 10 16 at. cm −3 ) Al-doped samples. A new IR absorptional at 992 cm −1 which is linearly correlated to the Al-doped concentration is found. It is suggested to originate from an oxygen vibration in a Si O Al center.

Local vibrational modes of a dicarbon–hydrogen center in crystalline silicon

Carbon-doped silicon irradiated with electrons at room temperature and subsequently implanted with protons has been studied by infrared absorption spectroscopy. Isochronal annealing in the temperat ...

Infrared absorption study of a new dicarbon center in silicon

Infrared absorption measurements on n-type silicon doped with carbon and irradiated with electrons at room temperature have revealed new absorption lines at 527.4 and 748.7 cm(-1). The 748.7 cm(-1) ...

The electronic structure of ZrN0.93(110) studied by angle-resolved photoemission

An angle-resolved photoemission study of a ZrN0.93 (110) single crystal is reported. Off-normal spectra recorded using unpolarized Ne I and He I resonance radiation are presented and the determined experimental peak dispersion are compraed with possible direct transitions calculated for ZrN1.0. The results show that dominant emission peaks at these photon energies probably are one-dimensional density of states features, i.e., peaks originating from band extrema. A peak observed at about 2eV below the Fermi energy is interpreted as originating from occupied vacancy states.