Papers by Keyword: Extended Defects

Abstract: The initial phase of defect propagation in broad area diode lasers, which are affected by the catastrophic optical damage (COD) effect, is studied. The decay of laser power within the first several 100 ns is found to be determined by defect propagation. When analyzing different device designs, a correlation is found between defect propagation velocities and thermal resistances of the materials vicinal to the quantum well, being the main heat source. The findings are confirmed by direct inspection of the defect pattern in opened devices.

Abstract: Admittance spectroscopy (AS) and deep level transient spectroscopy (DLTS) have been applied to B-doped thin polycrystalline diamond films deposited on p+-silicon by hot filament chemical vapour deposition. Films with two boron concentrations (1.5×10^19 cm-3 and 4×10^19 cm-3) were selected to study the effect of B concentration on the electronic states in CVD-diamond. We have investigated whether these deep states arise from point or extended defects. DLTS and AS find two hole traps, E1 (0.29±0.03 eV) and E2 (0.53±0.07 eV), in both films. A third level, E3 (0.36±0.02 eV) was also detected in the more highly doped film. The defect levels E1 and E2 exhibited behaviour typical of extended defects, which we suggest may be due to B segregated to the grain boundaries. In contrast, the defect level E3 exhibited behaviour characteristic of an isolated point defect, which we attribute to B-related centres in bulk diamond.

Abstract: The effect of extended defects on carrier lifetime was investigated in 140 um thick 4H-SiC epilayers using whole wafer ultraviolet photoluminescence (UVPL) and microwave photoconductive decay (uPCD) mapping. Half-loop arrays (HLA) seen in the UVPL images showed a corresponding lifetime degradation in the same region, even before expansion of the HLAs to form SFs. Lifetime lowering was also seen for a defect comprising of a small 3C-SiC inclusion with a larger misoriented 4H-SiC region. Additionally, formation of slip planes after high temperature annealing was observed, which consequently shows a lifetime reduction in that region.

Abstract: This contribution summarizes recent efforts to apply transmission electron microscopy (TEM) techniques to recombination-active extended defects present in a low density. In order to locate individual defects, electron beam induced current (EBIC) is applied in situ in a focused ion beam (FIB) machine combined with a scanning electron microscope. Using this approach defect densities down to about 10cm^-2 are accessible while a target accuracy of better than 50nm is achieved. First applications described here include metal impurity related defects in multicrystalline silicon, recombination and charge collection at NiSi₂ platelets, internal gettering of copper by NiSi₂ precipitates and site-determination of copper atoms in NiSi₂.

Abstract: Material defects such as Si-core and C-core partial dislocations (PDs) and threading screw dislocations (TSDs) and threading edge dislocations (TEDs) are being investigated for their contributions to device performances in 4H-SiC. Non-destructive electroluminescence and photoluminescence techniques can be powerful tools for examining these dislocations. In this report, these techniques were used to reveal the different spectral characteristics for the mentioned dislocations. At higher injection levels, both the Si-core and C-core PDs possessed a spectral peak at 700 nm. However, at lower injection levels, the spectral peak for the Si-core PD remained at 700 nm while the peak for the C-core moved to longer wavelengths. For the threading dislocations, TSDs possessed a peak between 800 and 850 nm while the TEDs possessed a peak at 600 nm independent of the injection levels.

Abstract: Silicon-based power device performances are largely affected by metal contamination occurring during device manufacturing. Among the usual gettering techniques, recent developments were done on high dose helium implantation. Even though the gettering efficiency of this technique has been demonstrated in device application, the required doses are still extremely high for an industrial application. Recently, it has been shown that the use of H/He co-implantation limits the total requested doses [1]. In this paper, co-implantation of H/He, which has been already used to reduce the dose in the smart-cut® process is explored. The goal of this work is to decrease efficiently the implanted dose maintaining an efficient metallic gettering without degrading the Si surface. The impact of H implantation on He implantation induced defects is carefully studied. The TEM observations have evidenced that hydrogen addition drastically modified the defect band structure and promotes the cavity growth.. Additionally, we demonstrate that an efficient gettering can be obtained.

Abstract: Deep electronic states associated with iron silicide precipitates have been studied by means of deep-level transient spectroscopy. The observed spectra show the characteristic features of bandlike states at extended defects. From the stability of the states on annealing at moderate temperature they are tentatively attributed to precipitate-matrix interfaces.