Diffusion capacitance

About: Diffusion capacitance is a research topic. Over the lifetime, 2427 publications have been published within this topic receiving 33948 citations.

Carrier Generation and Recombination in P-N Junctions and P-N Junction Characteristics

Abstract: For certain p-n junctions, it has been observed that the measured current-voltage characteristics deviate from the ideal case of the diffusion model. It is the purpose of this paper to show that the current due to generation and recombination of carriers from generation-recombination centers in the space charge region of a p-n junction accounts for the observed characteristics. This phenomenon dominates in semiconductors with large energy gap, low lifetimes, and low resistivity. This model not only accounts for the nonsaturable reverse current, but also predicts an apparent exp (qV/nkT) dependence of the forward current in a p-n junction. The relative importance of the diffusion current outside the space charge layer and the recombination current inside the space charge layer also explains the increase of the emitter efficiency of silicon transistors with emitter current. A correlation of the theory with experiment indicates that the energy level of the centers is a few kT from the intrinsic Fermi level.

Semiconductor device fundamentals

Abstract: I. SEMICONDUCTOR FUNDAMENTALS. 1. Semiconductors -- A General Introduction. General Material Properties. Crystal Structure. Crystal Growth. 2. Carrier Modeling. The Quantization Concept. Semiconductor Models. Carrier Properties. State and Carrier Distributions. Equilibrium Carrier Concentrations. 3. Carrier Action. Drift. Diffusion. Recombination -- Generation. Equations of State. Supplemental Concepts. 4. Basics of Device Fabrication. Fabrication Processes. Device Fabrication Examples. R1. Part I Supplement and Review. Alternative/Supplemental Reading List. Figure Sources/Cited References. Review List of Terms. Part I Review Problem Sets and Answers. IIA. PN JUNCTION DIODES. 5. PN Junction Electrostatics. Preliminaries. Quantitative Electrostatic Relationships. 6. PN Junction Diode -- I-V Characteristics. The Ideal Diode Equation. Deviations from the Ideal. Special Considerations. 7. PN Junction Diode -- Small-Signal Admittance. Introduction. Reverse-Bias Junction Capacitance. Forward-Bias Diffusion Admittance. 8. PN Junction Diode -- Transient Response. Turn-Off Transient. Turn-On Transient. 9. Optoelectronic Diodes. Introduction. Photodiodes. Solar Cells. LEDs. IIB. BJTS AND OTHER JUNCTION DEVICES. 10. BJT Fundamentals. Terminology. Fabrication. Electrostatics. Introductory Operational Considerations. Performance Parameters. 11. BJT Static Characteristics. Ideal Transistor Analysis. Deviations from the Ideal. Modern BJT Structures. 12. BJT Dynamic Response Modeling. Equivalent Circuits. Transient (Switching) Response. 13. PNPN Devices. Silicon Controlled Rectifier (SCR). SCR Operational Theory. Practical Turn-on/Turn-off Considerations. Other PNPN Devices. 14. MS Contacts and Schottky Diodes. Ideal MS Contacts. Schottky Diode. Practical Contact Considerations. R2. Part II Supplement and Review. Alternative/Supplemental Reading List. Figure Sources/Cited References. Review List of Terms. Part II Review Problem Sets and Answers. III. FIELD EFFECT DEVICES. 15. Field Effect Introduction -- the J-FET and MESFET. General Introduction. J-FET. MESFET. 16. MOS Fundamentals. Ideal Structure Definition. Electrostatics -- Mostly Qualitative. Electrostatics -- Quantitative Formulation. Capacitance-Voltage Characteristics. 17. MOSFETs -- The Essentials. Qualitative Theory of Operation. Quantitative ID - VD Relationships. ac Response. 18. Nonideal MOS. Metal-Semiconductor Workfunction Difference. Oxide Charges. MOSFET Threshold Considerations. 19. Modern FET Structures. Small Dimension Effects. Select Structure Survey. R3. Part III Supplement and Review. Alternative/Supplemental Reading List. Figure Sources/Cited References. Review List of Terms. Part III Review Problem Sets and Answers. Appendix A. Elements of Quantum Mechanics. Appendix B. MOS Semiconductor Electrostatics -- Exact Solution. Appendix C. MOS C-V Supplement. Appendix D. MOS I-Vsupplement. Appendix E. List of Symbols. Appendix M. MATLAB Program Script.

Scaling the Si MOSFET: from bulk to SOI to bulk

Abstract: Scaling the Si MOSFET is reconsidered. Requirements on subthreshold leakage control force conventional scaling to use high doping as the device dimension penetrates into the deep-submicrometer regime, leading to an undesirably large junction capacitance and degraded mobility. By studying the scaling of fully depleted SOI devices, the important concept of controlling horizontal leakage through vertical structures is highlighted. Several structural variations of conventional SOI structures are discussed in terms of a natural length scale to guide the design. The concept of vertical doping engineering can also be realized in bulk Si to obtain good subthreshold characteristics without large junction capacitance or heavy channel doping. >

Determination of defect distributions from admittance measurements and application to Cu(In,Ga)Se2 based heterojunctions

Abstract: A method to deduce energy distributions of defects in the band gap of a semiconductor by measuring the complex admittance of a junction is proposed. It consists of calculating the derivative of the junction capacitance with respect to the angular frequency of the ac signal corrected by a factor taking into account the band bending and the drop of the ac signal over the space charge region of the junction. Numerical modeling demonstrates that defect distributions in energy can be reconstructed by this method with high accuracy. Defect distributions of polycrystalline Cu(In,Ga)Se2 thin films are determined by this method from temperature dependent admittance measurements on heterojunctions of Cu(In,Ga)Se2 with ZnO that are used as efficient thin film solar cells.

dc SQUID: Noise and optimization

Abstract: A computer model is described for the dc SQUID in which the two Josephson junctions are nonhysteretic, resistively shunted tunnel junctions. In the absence of noise, current-voltage(I–V) characteristics are obtained as functions of the applied flux, Φ a , SQUID inductanceL, junction critical currentI 0 , and shunt resistanceR. The effects of asymmetry inL, I 0 , andR are discussed.I–V characteristics, flux-voltage transfer functions, and low-frequency spectral densities of the voltage noise are obtained at experimentally interesting values of the parameters in the presence of Johnson noise in the resistive shunts. The transfer functions and voltage spectral densities are used to calculate the flux and energy resolution of the SQUID operated as an open-loop, small-signal amplifier. The resolution of the SQUID with ac flux modulation is discussed. The flux resolution calculated for the SQUID of Clarke, Goubau, and Ketchen is1.6 × 10 −5 Φ 0 Hz−1/2 , approximately one-half the experimental value. Optimization of the SQUID resolution is discussed: It is shown that the optimum operating condition is β=2LI 0 /Φ 0 ≈1. Finally, some speculations are made on the ultimate performance of the tunnel junction dc SQUID. When the dominant noise source is Johnson noise in the resistive shunts, the energy resolution per Hz is4k B T(πLC) 1/2 , whereC is the junction capacitance, and the constraintR=(Φ 0 /2πCI 0 ) 1/2 has been imposed. This result implies that the energy resolution is proportional to (junction area) 1/2 . In the limiteI 0 R ≫k B T, the dominant noise source is shot noise in the junctions; for β=1, the energy resolution per Hz is then approximatelyh/2.