Jacob C. H. Phang

A comparative study of extraction methods for solar cell model parameters

Abstract A comparative study of three methods for extracting solar cell parameters of the single-diode lumped-circuit model is presented. The methods compared are the curve-fitting method, an iterative 5-point method and a recently proposed analytical 5-point method. Parameter values were extracted using these three methods from experimental characteristics collected from two silicon cells over a range of illuminations and temperatures. The results show that the curve-fitting method can often give erroneous parameter values and the reasons for the errors are discussed. The 5-point methods are found to be reliable and accurate in situations where the model is a good approximation of cell performance. The analytical 5-point method, however, has the added advantage of simplicity. It is also found that for the cell measured, the single diode model is valid at illuminations above one-half AM1 but gives non-physical parameter values at lower illumination.

A direct method for the extraction of diffusion length and surface recombination velocity from an EBIC line scan: planar junction configuration

A direct method of extracting bulk minority carrier diffusion length and surface recombination velocity from an EBIC line scan in the planar configuration is described. The accuracy of the method is verified by 3-D computer simulation and compared with existing methods. It mas found that this method is much simpler to use and gives better accuracy than existing methods. >

A review of near infrared photon emission microscopy and spectroscopy

Near infrared photon emission microscopy is an established fault localization technique for microelectronic failure analysis. Near infrared photon spectroscopy has the potential to become a useful defect characterization technique. In this paper, near infrared photon emission microscopy and spectroscopy are reviewed together with the instrumentation developments that allow these techniques to be effectively deployed for microelectronic failure analysis. The measurement results from pn junctions and saturated MOSFETs are correlated with the various photon emission mechanisms. Additional information that can be obtained from NIR systems over visible systems are also presented.

A review of laser induced techniques for microelectronic failure analysis

Recent developments have seen the use of scanning focused near infra-red (NIR) laser beams for fault localization and defect characterization in microelectronic failure analysis. Fault localization techniques are based on thermal stimulation and include power alteration techniques such as OBIRCH, TIVA, SEI, and tester based techniques such as RIL-SDL. Defect characterization techniques are based on carrier stimulation and include OBIC, SCOBIC and LIVA. A review of the concepts and application of these techniques together with the instrumentation requirements to effectively deploy these techniques are presented in this paper.

A direct and accurate method for the extraction of diffusion length and surface recombination velocity from an EBIC line scan

Abstract A new method is proposed for the determination of bulk minority carrier diffusion length and surface recombination velocity. This method uses data from an EBIC line scan in which the current collecting p − n junction or Schottky barrier is parallel to the electron beam. A 3-D computer simulation was used to verify the accuracy of the method. It was found that this method is simpler to use and more accurate than existing methods.

A review of curve fitting error criteria for solar cell I–V characteristics

Abstract Various methods for recovering solar cell lumped circuit model parameters from experimental characteristics are briefly reviewed. The advantages of extracting parameters from illuminated characteristics are highlighted. These include the availability of accurate analytical expressions developed recently. A commonly used method of parameter recovery by curve fitting minimises σ which is defined as the r.m.s. of the relative current errors between the experimental and theoretical characteristics. This method is demonstrated to be unreliable when used with characteristics which have been collected by linear analogue to digital systems, or which have certain data point distributions. A more reliable minimisation criterion ϵ is proposed. ϵ is based on the area difference between the experimental and theoretical characteristics. Computation experiments show that the use of ϵ results in much more accurate parameter recovery for both dark and illuminated characteristics, and that its accuracy is almost independent of data point distribution. ϵ also provides a good basis for comparing the quality of fit of theoretical models to experimental characteristics.

Dyadic Green’s function for aplanatic solid immersion lens based sub-surface microscopy

We present the derivation of the dyadic Greens function for the aplanatic solid immersion lens based microscopy system. The presented dyadic Greens function is general and is applicable at non-aplanatic points as well in the object plane. Thus, the electromagnetic wave formulation is used to describe the optical system without paraxial assumptions. Various important and useful properties of SIL based microscopy system are also presented. The effect of the numerical aperture of the objective on the peak intensities, resolutions and the depth of field are also reported. Some interesting longitudinal effects are also reported.

A simulation model for cathodoluminescence in the scanning electron microscope

An improved three-dimensional model for simulating cathodoluminescence (CL) in a semiconductor under electron-beam irradiation is described. The Monte Carlo method is used to simulate electron-beam-semiconductor interaction while F. Berz and H.K. Kuikens (1976) formulation is used to obtain the excess carrier distribution. Optical losses of photons both within the semiconductor and at the semiconductor-air interface are also accounted for in this model. This model has been used to simulate the CL intensity as a function of electron-beam voltage, beam incidence angle, surface recombination velocity, diffusion length, absorption coefficient, and surface dead-layer thickness. The radiation patterns over the top face of a specimen with flat geometry are also simulated. >

A complete and computationally efficient numerical model of aplanatic solid immersion lens scanning microscope

This paper presents a computational model for modeling an aplanatic solid immersion lens scanning microscope. The scanning microscope model consists of three subsystems, each of which can be computed as a separate system, connected to the preceding or succeeding subsystem through the input/output only. Numerical techniques are used to enhance the computational efficiency of each subsystem. A distinct merit of the proposed model is that it can be used to simulate imaging results for diverse setups of the scanning microscope, like various polarizations, numerical aperture, and different detector pinhole sizes. It allows the study and analysis of both theoretical aspects like achievable resolution, and practical aspects like expected images for different object patterns and experimental setups. Further, due to its computational efficiency, diverse large scale structures can be easily simulated in scanning microscope and good experimental approaches determined before indulging into the time consuming and costly process of experimentation.

Complete modeling of subsurface microscopy system based on aplanatic solid immersion lens

A general model of a subsurface microscopy system based on an aplanatic solid immersion lens (ASIL) is presented. This model is composed of three components: generation of incident light into the ASIL, interaction of the incident light with the sample, and imaging of the scattered light. Interaction of incident light with sample can be calculated numerically using electromagnetic scattering theory, while vector diffraction theory is used to treat the other two components. Examples of imaging small and extended scatterers are shown. For small scatterers, we show the differences between the actual resolution of the whole system and the resolution predicted by considering only one subsystem of the whole system. For extended scatterers, two types of illuminations-focusing light illumination and plane wave direct illumination-are used to image the scatterers, and observations are explained using interaction of the incident light with the sample.