47 research outputs found
Gate Stack Dielectric Degradation of Rare-Earth Oxides Grown on High Mobility Ge Substrates
We report on the dielectric degradation of Rare-Earth Oxides (REOs), when
used as interfacial buffer layers together with HfO2 high-k films (REOs/HfO2)
on high mobility Ge substrates. Metal-Oxide-Semiconductor (MOS) devices with
these stacks,show dissimilar charge trapping phenomena under varying levels of
Constant- Voltage-Stress (CVS) conditions, which also influences the measured
densities of the interface (Nit) and border (NBT) traps. In the present study
we also report on C-Vg hysteresis curves related to Nit and NBT. We also
propose a new model based on Maxwell-Wagner instabilities mechanism that
explains the dielectric degradations (current decay transient behavior) of the
gate stack devices grown on high mobility substrates under CVS bias from low to
higher fields, and which is unlike to those used for other MOS devices.
Finally, the time dependent degradation of the corresponding devices revealed
an initial current decay due to relaxation, followed by charge trapping and
generation of stress-induced leakage which eventually lead to hard breakdown
after long CVS stressing.Comment: 19pages (double space), 7 figures, original research article,
Submitted to JAP (AIP
Tunable Frohlich Polarons in Organic Single-Crystal Transistors
In organic field effect transistors (FETs), charges move near the surface of
an organic semiconductor, at the interface with a dielectric. In the past, the
nature of the microscopic motion of charge carriers -that determines the device
performance- has been related to the quality of the organic semiconductor.
Recently, it has been appreciated that also the nearby dielectric has an
unexpectedly strong influence. The mechanisms responsible for this influence
are not understood. To investigate these mechanisms we have studied transport
through organic single crystal FETs with different gate insulators. We find
that the temperature dependence of the mobility evolves from metallic-like to
insulating-like with increasing the dielectric constant of the insulator. The
phenomenon is accounted for by a two-dimensional Frohlich polaron model that
quantitatively describes our observations and shows that increasing the
dielectric polarizability results in a crossover from the weak to the strong
polaronic coupling regime
Unique presentation of a giant mediastinal tumor as kyphosis: a case report
<p>Abstract</p> <p>Introduction</p> <p>Although posture distortion is a common problem in elderly patients, spinal deformity caused by a thymoma has not been previously reported. Thymomas are slowly growing tumors that predominantly cause respiratory symptoms.</p> <p>Case presentation</p> <p>We report the case of an 83-year-old woman who was admitted with a giant mediastinal mass that had caused progressive spinal distortion and weight loss to our department. The clinical and laboratory investigations that followed revealed one of the largest thymomas ever reported in the medical literature, presenting as a mass lesion placed at the left hemithorax. She underwent complete surgical excision of the tumor via a median sternotomy. Two years after the operation, she showed significant improvement in her posture, no pulmonary discomfort, and a gain of 20 kg; she remains disease free based on radiographic investigations.</p> <p>Conclusions</p> <p>In this case, a chronic asymmetric load on the spine resulted in an abnormal vertebral curvature deformity that presented as kyphosis.</p
Primary parotid gland lymphoma: a case report
<p>Abstract</p> <p>Introduction</p> <p>Mucosa associated lymphoid tissue lymphomas are the most common lymphomas of the salivary glands. The benign lymphoepithelial lesion is also a lymphoproliferative disease that develops in the parotid gland. In the present case report, we describe one case of benign lymphoepithelial lesion with a subsequent low transformation to grade mucosa associated lymphoid tissue lymphoma appearing as a cystic mass in the parotid gland.</p> <p>Case presentation</p> <p>A 78-year-old Caucasian female smoker was referred to our clinic with a non-tender left facial swelling that had been present for approximately three years. The patient underwent resection of the left parotid gland with preservation of the left facial nerve through a preauricular incision. The pathology report was consistent with a low-grade marginal-zone B-cell non-Hodgkin lymphoma (mucosa associated lymphoid tissue lymphoma) following benign lymphoepithelial lesion of the gland.</p> <p>Conclusions</p> <p>Salivary gland mucosa associated lymphoid tissue lymphoma should be considered in the differential diagnosis of cystic or bilateral salivary gland lesions. Parotidectomy is recommended in order to treat the tumor and to ensure histological diagnosis for further follow-up planning. Radiotherapy and chemotherapy should be considered in association with surgery in disseminated forms or after removal.</p