Effective Generation Lifetime (τg,eff) and Surface Generation Velocity (Seff) Extractions Via Zerbst Plot Analysis

Capacitance vs. time (c-t) characteristics of a MOS structure show the capacitance change after a pulse bias is applied which drives the structure first into accumulation then into deep inversion. Since the time constant of minority carrier generation is relatively long, the MOS structure requires time to reach equilibrium after the pulse bias is applied. Immediately after the pulse bias is applied, the depletion layer extends more widely then the depletion layer becomes narrower - the MOS structure approaches equilibrium as more and more minority carriers are generated. Finally, the depletion layer reaches its equilibrium width. This proves charge neutrality. The C-t characteristics are obtained from this change in the depletion layer width. During this project, capacitance vs. time measurements were made using an external bias source. The system consists of a probe station located within a dark box, a Keithley K182 system and a ICS metrics software. The measured capacitance-time (C-t) data were converted into a Zerbst plot using the Zerbst equation. The effective generation lifetime (τg,eff) and the surface generation velocity (seff) were extracted from the slope and the intercept of the Zerbst plot. The main problem with this technique is that times of hundreds or even thousands of seconds per measurement are not uncommon. One method of optical excitation to reduce this measurement time was investigated. We have achieved our goal: setup the pulsed MOS capacitor recombination lifetime measurement technique in the JUT test area. Besides this project did not require the purchase of hardware or additional software. Finally we have shown that the total measurement time was significantly reduced by illumination and there was virtually no error compared to the curve recorded entirely in the dark

Journal of Microelectronic Research - May 2003

https://scholarworks.rit.edu/meec_archive/1012/thumbnail.jp

Galvanic corrosion of stacked metal gate electrodes during cleaning in HF solutions

This work demonstrates that future metal gate electrodes can form a galvanic cell in dilute HF solutions and can result in an increased corrosion of the less noble material. In the worst case, it could lead to fully removal of small gate electrodes during wet processing. Depending on the gate stack and the integration scheme, the galvanic corrosion at the gate could be a major problem. In this case, dissolved oxygen and flow rate of the HF mixture during cleaning offer opportunities to minimize the galvanic corrosion impact.status: publishe

CXCL13-producing TFH cells link immune suppression and adaptive memory in human breast cancer.

T follicular helper cells (TFH cells) are important regulators of antigen-specific B cell responses. The B cell chemoattractant CXCL13 has recently been linked with TFH cell infiltration and improved survival in human cancer. Although human TFH cells can produce CXCL13, their immune functions are currently unknown. This study presents data from human breast cancer, advocating a role for tumor-infiltrating CXCL13-producing (CXCR5-) TFH cells, here named TFHX13 cells, in promoting local memory B cell differentiation. TFHX13 cells potentially trigger tertiary lymphoid structure formation and thereby generate germinal center B cell responses at the tumor site. Follicular DCs are not potent CXCL13 producers in breast tumor tissues. We used the TFH cell markers PD-1 and ICOS to identify distinct effector and regulatory CD4+ T cell subpopulations in breast tumors. TFHX13 cells are an important component of the PD-1hiICOSint effector subpopulation and coexpanded with PD-1hiICOSintFOXP3hi Tregs. IL2 deprivation induces CXCL13 expression in vitro with a synergistic effect from TGFβ1, providing insight into TFHX13 cell differentiation in response to Treg accumulation, similar to conventional TFH cell responses. Our data suggest that human TFHX13 cell differentiation may be a key factor in converting Treg-mediated immune suppression to de novo activation of adaptive antitumor humoral responses in the chronic inflammatory breast cancer microenvironment.SCOPUS: ar.jinfo:eu-repo/semantics/publishe