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In this paper, the physical mechanisms involved in electron-beam-induced current (EBIC) imaging of semiconductor pn-junctions are reviewed to propose a model and optimize the acquisition of experimental data. Insights are drawn on the dependence of the EBIC signal with electron accelerating voltage and surface conditions. It is concluded that improvements in the resolution of EBIC are possible when the surface conditions of the specimens are carefully considered and optimized. A lower accelerating voltage and an increase of the surface recombination velocities are quantitatively shown to maximize the EBIC lateral resolution in locating the pn-junction. The effect of surface band bending is included in the model, and it is seen to primarily affect the surface recombination. Introducing controlled surface damage is shown as a potential method for resolution enhancement via focused ion beam milling with Ga+ ions. These findings contribute to the understanding of this technique and can produce further improvements to its application in semiconductor device technology. [ABSTRACT FROM AUTHOR]

The recombination of electric charge carriers at semiconductor surfaces continues to be a limiting factor in achieving high performance optoelectronic devices, including solar cells, laser diodes, and photodetectors. The theoretical model and a solution algorithm for surface recombination have been previously reported. However, their successful application to experimental data for a wide range of both minority excess carrier concentrations and dielectric fixed charge densities has not previously been shown. Here, a parametrisation for the semiconductor-dielectric interface charge Qit is used in a Shockley-Read-Hall extended formalism to describe recombination at the c-Si/SiO2 interface, and estimate the physical parameters relating to the interface trap density Dit, and the electron and hole capture cross-sections rn and rp. This approach gives an excellent description of the experimental data without the need to invoke a surface damage region in the c-Si/SiO2 system. Band-gap tail states have been observed to limit strongly the effectiveness of field effect passivation. This approach provides a methodology to determine interface recombination parameters in any semiconductor-insulator system using macro scale measuring techniques. [ABSTRACT FROM AUTHOR]

Hydrogen passivation is a key industrial technique used to reduce the recombination activity of defects in multicrystalline silicon (mc‐Si). However, not all dislocations and grain boundaries respond well to traditional hydrogen passivation techniques. In order to understand the reasons for these different behaviours, and how superior passivation might be achieved, a method is required for the direct observation of hydrogen at these defects. Here, we present a novel characterisation technique based on a combination of transmission Kikuchi diffraction (TKD), atom probe tomography (APT), and isotopic substitution that enables unambiguous detection and quantification of hydrogen atoms present at crystallographic defects in mc‐Si. [ABSTRACT FROM AUTHOR]

In this article, field-effect surface passivation is characterised as either intrinsic or extrinsic, depending on the origin of the charges present in passivation dielectric layers. The surface recombination velocity of float zone, 1 Ω cm, n-type silicon was reduced to 0.15 cm/s, the lowest ever observed for a passivating double layer consisting of thermally grown silicon dioxide and plasma enhanced chemical vapour deposited silicon nitride. This result was obtained by enhancing the intrinsic chemical and field-effect passivation of the dielectric layers with uniform, extrinsic fieldeffect passivation induced by corona discharge. The position and stability of charges, both intrinsic and extrinsic, were characterised and their passivation effect was seen stable for two months with surface recombination velocity <2 cm/s. Finally, the intrinsic and extrinsic components of passivation were analysed independently. Hydrogenation occurring during nitride deposition was seen to reduce the density of interfacial defect states from ~5×1010 cm–2eV–1 to ~5×109 cm–2eV–1, providing a decrease in surface recombination velocity by a factor of 2.5. The intrinsic charge in the dielectric double layer provided a decrease by a factor of 4, while the corona discharge extrinsic field-effect passivation provided a further decrease by a factor of 3. [ABSTRACT FROM AUTHOR]

Nanocrystalline silicon carbide (nc-SiC) is an interesting material for electronics applications, both in its own right and as a host matrix for silicon quantum dots. When synthesized by annealing of a-SiC:H on Si substrates, interdiffusion of dopants occurs if either the a-SiC:H or the Si substrate is doped. Annealing a-SiC:H on highly boron-doped substrates at 1100 °C leads to a fairly homogeneous doping level of ≥4×1019 cm-3 throughout the nc-SiC film. An unexpected anomaly in secondary ion mass spectroscopy quantification is observed and a method to circumvent it is shown. The nanostructure of the nc-SiC is only weakly affected as most of the diffusion occurs after the onset of crystallization. Annealing of doped a-SiC:H on Si substrates at 1100 °C leads to strong free carrier absorption at infrared wavelengths. This is demonstrated to originate from dopants that have diffused from the a-SiC:H to the Si substrate, and a method is developed to extract from it the doping profile in the Si substrate. The detection limit of this method is estimated to be ≥6×1013 cm-2. Doping levels of (0.5-3.5)×1019 cm-3 are induced at the Si substrate surface by both boron and phosphorus-doped a-SiC:H. When the Si substrate is doped opposite to the a-SiC:H p-n junctions are induced at a depth of 0.9-1.4 lm within the Si substrate for substrate resistivities of 1-10 Ω cm. Implications for different solar cell architectures are discussed. Dopant diffusion can be strongly reduced by lowering the annealing temperature to 1000 °C, albeit at the expense of reduced crystallinity. [ABSTRACT FROM AUTHOR]

Dielectric double layers of thermal silicon dioxide-chemical vapour deposition (CVD) silicon nitride are found to produce excellent passivation of silicon surfaces by combining a chemical reduction of surface defect states, with a field effect reduction of carriers at the surface due to charge in the dielectrics. The charge present in such double-layers has previously been attributed to be characteristic of the interface between the two. However, experimental evidence shows this is indirect and inconclusive. This manuscript reports direct measurements that show the charge lies within 10 nm of the interface between passivating double layers of thermal silicon dioxide-plasma CVD silicon nitride. In addition, the passivation efficiency of oxide-nitride layers, deposited using optimised conditions, was found to be largely unaffected by extra charge subsequently added to the film. The passivation efficiency of textured surfaces or those produced using non-optimised deposition conditions is found to be highly dependent on the field effect component provided by extra deposited charge. Using such extra field effect component, surface recombination velocities <2 cm/s have been obtained on single oxide and oxide/nitride double layers. The extra deposited charge was found to have good long term stability when the dielectric films are submitted to a chemical treatment. By contrast, poor stability of the deposited charge was observed when subjected to ultraviolet radiation. These results point to the importance of the interface between dielectrics when considering how to optimise the charge present in passivating dielectric films. [ABSTRACT FROM AUTHOR]