L. I. Pomortseva

Bio: L. I. Pomortseva is an academic researcher. The author has contributed to research in topics: Silicon & Doping. The author has an hindex of 3, co-authored 4 publications receiving 20 citations.

Investigation into the effect of Auger recombination on charge carrier transport and static characteristics of silicon multilayer structures

Abstract: A new model for charge carrier transport through a silicon multilayer structure at high current density is presented. This model accounts for a number of nonlinear physical phenomena (electron-hole scattering, Auger recombination, high doping effects) which become of significance at high current density. The injected charge carrier distribution in the lightly doped layer of the structure at high current density was investigated on the basis of this model and previously predicted phenomenon of injected carrier saturation is confirmed. The dependence of injected carrier limiting density on the electrophysical parameters of the silicon structure was investigated. Within the framework of the suggested model the current-voltage characteristics of a p+-n-n+ structure was studied. It is demonstrated that injected carrier saturation phenomenon results in linear current-voltage characteristics at high current densities. A characteristic ratio (WL)c (where W is the width of the n-base layer and L is the ambipolar diffusion length of charge carriers in the n-base layer) was found to divide the diode structures into two groups. In the first group with WL (WL)c retains a dependence on τ at all current densities. Experimental data presented in the last section of the article confirm the results of device modeling.

Effect of nonlinear physical phenomena on the photovoltaic effect in silicon p + -n-n + solar cells

Abstract: The influence of the combined effects of high injection level and heavy doping on the characteristics of silicon p + –n–n + solar cells is examined. The total amount of nonlinear physical phenomena (Auger recombination, electron-hole scattering, band-gap narrowing, charge carrier lifetime and transport coefficient reduction in the heavily doped layers of the structure) is taken into account. It has been established that a combined process which includes the generated charge carrier overflowing from n-base layer to highly doped n + -type and p + -type layers of the structure and their subsequent recombination in these highly doped layers, proves to be of great importance in silicon solar cells. The influence of electron-hole scattering on charge carrier transport in the highly doped n + -type and p + -type layers has been investigated for the first time. It has been found that minority carrier complete drag phenomenon results in a significant decrease of n + -type and p + -type layer saturation currents.

Electron-hole scattering in p -type silicon with a low charge-carrier injection level

Abstract: A previously proposed method for determining the parameters of electron-hole scattering in indirect-gap semiconductors is used to investigate the properties of p-type silicon. Diode n +-p-p + structures were used for the measurements. The results obtained by us indicate that complete dragging of the minority electrons by the majority holes is possible, even at room temperature, in p-type material with doping levels N>1018 cm−3.

Study on feasibility of minority carrier complete drag in silicon. New investigation method intended for indirect-gap semiconductors

Abstract: A method is proposed for determining the electron - hole scattering parameters in indirect gap semiconductors when the carrier injection level is low. The proposed method is used to study the electron - hole scattering in silicon. The results are evidence that minority carrier complete drag by majority-electrons is possible in n-type material at a doping level of Nd > 10 17 cm -3 even at room temperatures.

Imaging Charge Separation and Carrier Recombination in Nanowire p-i-n Junctions Using Ultrafast Microscopy

Abstract: Silicon nanowires incorporating p-type/n-type (p-n) junctions have been introduced as basic building blocks for future nanoscale electronic components. Controlling charge flow through these doped nanostructures is central to their function, yet our understanding of this process is inferred from measurements that average over entire structures or integrate over long times. Here, we have used femtosecond pump–probe microscopy to directly image the dynamics of photogenerated charge carriers in silicon nanowires encoded with p-n junctions along the growth axis. Initially, motion is dictated by carrier–carrier interactions, resulting in diffusive spreading of the neutral electron–hole cloud. Charge separation occurs at longer times as the carrier distribution reaches the edges of the depletion region, leading to a persistent electron population in the n-type region. Time-resolved visualization of the carrier dynamics yields clear, direct information on fundamental drift, diffusion, and recombination processes ...

Analytical and numerical studies of p+-emitters in silicon carbide bipolar devices

Abstract: In this paper, ways to create silicon carbide p+-emitters with high injection coefficients are considered. Raising the emitter doping level, eliminating the deteriorated layer, and making longer the electron lifetime in the emitter are discussed and analyzed. The efficiency criteria are established for SiC emitters by comparing Si and SiC p+–n junctions. It is shown that the properties of modern SiC p+-emitters are far from being optimal. Analytical models have been developed to describe the properties of SiC p+–n junctions in terms of the well-known 'saturation current' (jsn) approach, which takes into account the main nonlinear effects that govern the transport phenomena in highly doped emitter layers: bandgap narrowing, Auger recombination, electron–hole scattering, radiative recombination, and surface recombination. It is demonstrated that the value of jsn for the SiC p+–n junction may be as small as ~2 × 10−49 A cm−2, i.e. two orders of magnitude smaller than the smallest values of jsn in modern SiC bipolar devices. The dependences of jsn on the electron lifetime and doping level in the emitter are analyzed. It is shown that the electron lifetime in the p+-emitter layer has a vigorous effect on the device forward voltage. The analytical results are confirmed by the data furnished by numerical experiments.

Effect of high injection level phenomena on the feasibility of diffusive approximation in semiconductor device modeling

Abstract: The influence of nonlinear physical phenomena (namely electron-hole scattering, Auger recombination, reduction of the emitter junction efficiency) on the practicality of diffusive approximation in semiconductor multilayer device modeling is investigated. It is shown that there exists a certain sequence of proper approximations as the current density increases. An important point is that this sequence of approximations depends on the electrophysical parameters of the structure, namely on the ratio W / L (where W is the width of the lightly doped base layer of the structure, L is the ambipolar diffusion length of charge carriers in the base layer), the charge carrier lifetime τ and the saturation current j sn and j sp of the highly doped p + and n + layers.

Parameters of electron–hole scattering in silicon carbide

Abstract: The parameters of electron–hole scattering (EHS) in silicon carbide (SiC) are estimated by analyzing pulsed isothermal current–voltage characteristics of 6.0 kV 4H–SiC diodes over a wide range of current densities (100–104 A/cm2) and external temperatures (293–553 K). The efficiency of EHS in SiC is approximately two times higher than that in Si and 60 times higher than that in GaAs. The EHS makes a very essential contribution to voltage drop across SiC bipolar devices at high forward current densities.

On the transport equations in popular commercial device simulators

Abstract: The transport formulation used in many commercial semiconductor device simulators (for example DESSIS, ATLAS, and MEDICI) does not allow accurate modeling of electron-hole scattering in bipolar semiconductor devices such as diodes, bipolar junction transistors, and thyristors. This is especially important at low temperatures and/or high current densities.