Temperature dependence of contact resistance of Au-Ti-Pd2Si-n+-Si ohmic contacts

We investigated temperature dependence of contact resistance of an Au-Ti-Pd2Si ohmic contact to heavily doped n+-Si. The contact resistance increases with temperature owing to conduction through the metal shunts. In this case, the limiting process is diffusion input of electrons to the metal shunts. The proposed mechanism of contact resistance formation seems to realize also in the case of wide-gap semiconductors with high concentration of surface states and dislocation density in the contact

Evaluation of remote results of surgical treatment of nodular endemic goiter with autoimmune thyroiditis

Introduction. Autoimmune thyroiditis is one of the most important problems of modern endocrinology, with inadequately studied etiological and pathogenic mechanisms of development. It is characterized by the lack of objective and reliable diagnostic methods, effective treatment methods, uncertain therapy or indications for the choice of treatment methods. The aim of the study. Determination of markers for prediction of clinical course and choice of surgery’ volume in patients with nodular goiter and autoimmune thyroiditis, taking into account the oxidative, autoimmune and apoptotic processes. Material and methods. A total of 95 patients who were operated for a nodular endemic goiter on the background of autoimmune thyroiditis were examined. The status of pro- and antioxidant systems, the activity of proinflammatory cytokines, hormonal function of thyroid gland, the level of antibodies to thyroperoxidase, thyroglobulin antibodies and ultrasound structural changes in the thyroid gland have been evaluated in all patients, before and after surgery. Results. In patients with nodular endemic goiter and autoimmune thyroiditis, in the remote period after surgical treatment, there is a significant increase in the peroxide oxidation index and a decrease in the activity of antioxidant defense systems, against the suppression of apoptotic processes and the activation of pro-inflammatory cytokines. These processes lead to functional failure, hyperplasia and the progression of structural thyroid abnormalities, with progression of the functional incapacity of the thyroid gland and inadequate long-term outcome of treatment. Conclusions. The study allowed to clarify the indications and contraindications of different methods of treatment in patients with NGAIT, taking into account the parameters of severity of peroxide oxidation processes, the activity of apoptosis and functional capacity of the gland

АНАЛІЗ ПРОЦЕСІВ ПЕРОКСИДНОГО ОКИСНЕННЯ, КАСПАЗИ-3 ТА КАСПАЗИ-8 У ХВОРИХ НА ВУЗЛОВІ ФОРМИ ЗОБА НА ФОНІ АВТОІМУННОГО ТИРЕОЇДИТУ ТА З АДЕНОМОЮ ЩИТОПОДІБНОЇ ЗАЛОЗИ

In the article presented the results of analysis processes peroxidation activity, caspase-3 and caspase-8 in the tissue of patients with thyroid adenoma and nodular goiter with autoimmune thyroiditis. In the study of processes peroxidation in tissue thyroid found that the diseased modified tissue is a significant growth parameters of oxidative modification of proteins at the same time, the activity of enzyme antioxidant protection is significantly reduced, and more likely in patients with nodular goiter with autoimmune thyroiditis. It is shown that in patients with nodular goiter with autoimmune thyroiditis is a significant increase of the activity of caspase 3 and 8 as compared to not macroscopically altered tissue and thyroid adenoma. Discussed of possible mechanisms of these disorders.В статье приведены результаты сравнительного анализа активности процессов перекисного окисления, каспазы-3 и каспазы-8 в ткани у больных аденомой щитовидной железы и с узловым зобом на фоне аутоиммунного тиреоидита. При исследовании процессов перекисного окисления в ткани щитовидной железы выявлено, что в измененной патологическим процессомткани имеет место существенный рост параметров окислительной модификации белков, в то же время, активность ферментов антиоксидантной защиты существенно уменьшалась, причем более вероятно у больных с узловым зобом на фоне аутоиммунного тиреоидита. Показано, что у больных с узловым зобом на фоне аутоиммунного тиреоидита имеет место достоверное повышение активности каспазы 3 и 8 как по сравнению с макроскопически не изменены тканью, так и с аденомой щитовидной железы. Обсуждаются возможные механизмы выявленных нарушений.У статті наведено результати порівняльного аналізу активності процесів пероксидного окиснення, каспази-3 та каспази-8 в тканині у хворих на аденому щитоподібної залози (ЩЗ) та вузловий зоб на фоні автоімунного тиреоїдиту (ВЗАІТ). При дослідженні процесів пероксидного окиснення у тканині ЩЗ виявлено, що в патологічно зміненій тканині має місце суттєве зростання параметрів окислювальної модифікації білків (ОМБ), в той же час, активність ферментів антиоксидантного захисту (АОЗ) суттєво зменшувалась, причому більш вірогідно у хворих на ВЗАІТ. Показано, що у хворих на ВЗАІТ має місце вірогідне зростання активності каспази 3 та 8 як порівняно з макроскопічно незміненою тканиною, так і з аденомою ЩЗ. Обговорюються можливі ме¬ханізми виявлених порушень

Mechanism of contact resistance formation in ohmic contacts with high dislocation density

A new mechanism of contact resistance formation in ohmic contacts with high dislocation density is proposed. Its specific feature is the appearance of a characteristic region where the contact resistance increases with temperature. According to the mechanism revealed, the current flowing through the metal shunts associated with dislocations is determined by electron diffusion. It is shown that current flows through the semiconductor near-surface regions where electrons accumulate. A feature of the mechanism is the realization of ohmic contact irrespective of the relation between the contact and bulk resistances. The theory is proved for contacts formed to III-V semiconductor materials as well as silicon-based materials. A reasonable agreement between theory and experimental results is obtained. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3702850

InP Gunn diodes with a cathode contact injecting hot electrons. Part 1. Interactions between phases in the cathode contacts

The article presents the research on interactions between phases in the Ge–Au, Ge–TiBx and Au–TiBxAu contacts to n–n+–n++-InP, both before and after rapid thermal annealing, and also the output parameters of Gunn diodes based on the InP structure with Au–TiBx–Au–Ge contact metallization in the –40...+60 °С temperature range. It is shown that ohmic contacts to InP layer are formed as a result of diffusion of Ge and Au atoms deep inside the layer. The output parameters of Gunn diodes with Au–TiBx–Au–Ge cathode contacts agree with the data obtained for InP Gunn diodes made with the use of more complicated technology