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Stepped drift region thickness technique alters the drift region doping dose and its distribution, and therefore modulates the device's off-state characteristics. However, due to the sophisticated structure of the 2-D stepped drift region, the conventional 2-D modeling method is too complicated to provide a clear physical meaning. In this paper, based on the Effective Concentration Profile (ECP) theory, a simple but accurate 1-D ECP concept is proposed to unveil the physical insight of the stepped drift region technique and quantitatively analysis the influence of which on device breakdown characteristic. Therefore, the sophisticated 2-D structure affected by both RESURF and curvature effects is explored by a simple 1-D model with segmented-doped PN junction. Furthermore, based on the proposed analytical model, the designing criterion is proposed, which provide useful guidance for utilizing the benefit of the Stepped Drift Region Thickness technique and thus realizing the optimized surface electric field and breakdown voltage. The results obtained by the proposed model are found to be sufficiently accurate comparing with TCAD simulation results.

The drift region shape factor (Ld/t) plays a sophisticated role in affecting reduced surface field (RESURF) effect and breakdown characteristics. In this paper, based on the effective doping concentration (EDC) theory, an Improved EDC concept is proposed to explore the impact of shape factor on 2-D coupling effect in RESURF lateral power devices. The Improved EDC concept indicates that the sophisticated 2-D coupling in N-well resulting an effective N-I-P type drift region. Thus, the surface electric field basin may exist because of the expansion of vertical depletion region. The proposed model presents a more adaptive trait in describing 2-D coupling effect under various device structure parameters when compared to the conventional EDC model. Furthermore, a corresponding structure optimization criterion is provided to further improve the tradeoff between breakdown voltage, On-resistance and costs. The results obtained by the proposed model are found to be accurate comparing with TCAD simulation results.

The drift region doping profile plays a significant role in affecting the performance of lateral power devices on silicon-on-insulator (SOI) substrate. However, due to the modeling difficulty of the 2-D solution, the physical meaning of which still remains unclear. Thus, a novel effective doping profile concept is proposed to explore the physical insight of the surface electric field (EF) reshaping as a result of the step lateral doping profile. Through the effective concentration profile (ECP) theory, the sophisticated 2-D relationship between lateral step doping profile (SDP) and reduced surface field (RESURF) effect can be simplified to the fluctuation of the 1-D effective doping profile. A 1-D ECP model is presented accordingly to qualitatively and quantitatively explore the influence of SDP on the surface EF and breakdown voltage (BV) improvements. Furthermore, the designing criterion of drift region SDP is proposed with the help of the analytical model, which provides a useful guidance for realizing the optimized surface EF and BV in devices with SDP. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Unlike single layer graphene, in the case of AB -stacked bilayer graphene (BLG) one can induce a non-zero energy gap by breaking the inversion symmetry between the two layers using a perpendicular electric field. This is an essential requirement in field-effect applications, particularly since the induced gap in BLG systems can be further tuned by the magnitude of the external electric field. Doping is another way to modify the electronic properties of graphene based systems. We investigate here BLG systems doped with boron and nitrogen in the presence of external electric field, in the framework of density functional theory (DFT) calculations. Highly doped BLG systems are known to behave as degenerate semiconductors, where the Fermi energy depends on the doping concentration but, in addition, we show that the electronic properties drastically depend also on the applied electric field. By changing the magnitude and the orientation of the electric field, the gap size and position relative to the Fermi level may be tuned, essentially controlling the effect of the extrinsic doping. In this context, we discuss in how far the external electric field may suitably adjust the effective doping and, implicitly, the conduction properties of doped BLG systems. [ABSTRACT FROM AUTHOR]

The field-plate (FP) technique suppresses the electric field crowding at the p-n junction by inducing the interface charges in the drift region. However, due to the modeling difficulty, the physical meaning cannot be elaborated via the conventional 2-D methods, not to mention the designing optimization. Therefore, the FP assistant reduced surface field effective concentration profile (ECP) is proposed in this paper to explore the physical insight of the FP assistant 2-D coupling. The ECP simplifies the sophisticated 2-D coupling by equating the FP assistant effect to the variation of the ECP. As a result, a simple and effective 1-D analytical model is presented to qualitatively and quantitatively explore the FP-induced surface field reshaping and its distinctive breakdown mechanism. The analytical solutions are found out to be consistent with the simulation results obtained from MEDICI, a commercial TCAD tool. [ABSTRACT FROM AUTHOR]

The layout-induced cylindrical breakdown may occur as a result of the multifinger or circular layout-induced 3-D curvature effect resulting in the breakdown voltage reduction of the power device significantly. In this paper, by using effective doping concentration (EDC) concept, the inherent 3-D problem is simplified as a 1-D problem. Based on the EDC concept, a 1-D analytical model is presented to qualitatively and quantitatively explore the impact of curvature effect on the breakdown mechanism of SOI lateral double diffused MOS. The analytical solutions are found out to be consistent with the simulation results well obtained from MEDICI, a commercial technology computer-aided design tool. To the best of our knowledge, the proposed model is the first 1-D model which can accurately describe the 3-D curvature effect. [ABSTRACT FROM AUTHOR]

Double-reduced surface field (D-RESURF) technique aims to increase the doping concentration of drift regions and maintain a high breakdown voltage. However, conventional 2-D models are too complicated and unable to elaborate its physicalmeaning.Hence, the D-RESURF effective doping concentration (EDC) theory is proposed in this paper to explore the physical insight of the D-RESURF effect by equating the sophisticated 2-D structure to a simple 1-DRESURFmodelwith segmented-dopedp-n junction.The EDC indicates that an NPNP structure may exist because of the influence of the P-top region. Thus, two electric field valleys and one electric field peak can be formed on the surface. Based on the theory, a 1-D analytical model is presented to qualitatively and quantitatively explore the impact of D-RESURF effect on breakdown mechanism of silicon on insulator lateral double diffusion MOS. The results obtained by the proposedmodel are found to be suf- ficiently accurate comparing with TCAD simulation results. [ABSTRACT FROM AUTHOR]

ABSTRACT The effective doping concentration of the bulk of a silicon wafer is an important material parameter for photovoltaic applications. The techniques commonly used to measure the effective doping concentration are based on conductance or resistivity measurements and include both contacted methods, such as the four-point probe, and contactless approaches, such as eddy current measurements. Applying these techniques to diffused wafers is complicated by the fact that the total conductance is the sum of the bulk conductance and the diffused layer conductance. Without further information about the emitter properties, a clear separation of these two parameters is not possible. This paper demonstrates a contactless method for specifically measuring the effective doping concentration of the bulk without significant influence from diffused layers. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This work had as main objective the determination of a characteristic quantity of a potential well which is surfasic density Ns. This parameter is very important given its importance to the mobility of two-dimensional electron gas using the concept of effective doping that we allowed to study the influence of different technological parameters on the performance of AlGaAs/GaAs heterojunction which we will consider later dynamic study of HEMT transistor in a rigorous and complete manner. [ABSTRACT FROM AUTHOR]

In future high-energy physics experiments on silicon detectors will be widely used in extremely intense hadronic radiation. These high radiation levels will cause significant bulk damage, which leads to degradation of macroscopic properties of silicon detectors. Although several models have been presented to predict effective doping concentration (Neff) and leakage current in hadron irradiated silicon detectors, only inter-center charge transfer mechanism with non-Shockley-Read-Hall (SRH) statistics is satisfactory. From previous works it is evident that electron and hole cross-sections of defects that can participate in inter-center charge transfer have important effects on electrical parameters and especially Neff, but for most defects there are no data or only one of these cross-sections is known and usually at points much lower than room temperature. To model the hadron irradiated silicon detectors we used the extrapolated room temperature cross-sections of different levels of (V2) defect to estimate the important cross-sections of E70, E170 and inter-level cross-sections from leakage current data before and after annealing. This method, which is a more realistic model to estimate Neff, can be used to explain “proton–neutron puzzle” more precisely and gives useful information about the clustered defects that are responsible for reverse annealing in hadron irradiated silicon detectors. In addition, in this paper it was tried to present a qualitative explanation for “saturation of reverse annealing” in proton irradiated oxygenated silicon detectors, which can be the key for manufacturing more radiation-hard silicon detectors in the future. [Copyright &y& Elsevier]