Search

In order to obtain the detailed information on the conduction mechanisms of the Au/n-GaAs Schottky barrier diode (SBD), the current-voltage (I-V) characteristics were carried out in the temperature range of 80-340 K by the steps of 20 K. The ideality factor (n) decreases, while the effective barrier height (Phi(Bo)) increases with increasing temperature (80-340 K). The semilogarithmic I-V curve is almost parallel for each temperature. Therefore, its slope and tunneling parameter (E-oo) remained almost constant as independent of temperature with an average of 27.47 V-1 and 28.04 meV, respectively. Furthermore, the reverse saturation current (I-s) ranges, indication that the charge transport mechanism in the Au/n-GaAs SBD is tunneling due to the weak temperature dependence of the I-s. Thus, it can be said that the experimental I-V data quite well obey the thermionic field emission (TFE) model especially at low temperatures rather than the other transport mechanisms. On the other hand, an abnormal decrease in the Phi(Bo) and increase in the n with decreasing temperature have been observed which leads to non-linearity in the activation energy plots and a linear relationship between the barrier heights (BHs) and the ideality factors of the SBD. The high value of n especially at low temperatures cannot be also explained only TFE theory. Therefore, we tried to explain the non-ideal behavior of the forward-bias I-V characteristics in Au/n-GaAs SBD with the basis of a thermionic emission (TE) mechanism with a Gaussian distribution (GD) of the BHs. The obtained results show that the temperature dependence of forward bias I-V characteristics of the Au/n-GaAs SBD can be successfully explained in terms of the TE mechanism with a double GD of BHs for low bias region (LBR) and moderate bias region (MBR). (C) 2013 Elsevier B.V. All rights reserved.

The forward and reverse bias currentevoltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics of the Au/PVA (Bi-doped)/n-Si Schottky barrier diodes (SBDs) have been investigated at room temperature by taking the interface states (N-ss) and series resistance (R-s) effects into account. The voltage dependent profiles of resistance (R-i) were obtained from both the I-V and C/G-V measurements by using Ohm's Law and Nicollian methods. The obtained values of R-i with agreement each other especially at sufficiently high bias voltages which correspond the value of R-s of the diode. Therefore, the energy density distribution profile of N-ss was obtained from the forward bias I-V data taking the bias dependence of the effective barrier height (BH) Phi(e) and R-s into account. The high value of ideality factor (n) was attributed to high density of N-ss and interfacial polymer layer at metal/semiconductor (M/S) interface. In order to examine the frequency dependence of some of the electrical parameters such as doping donor concentration (N-D), Phi(e), R-s and N-ss values, C-V and G/omega-V measurements of the diode were performed at room temperature in the frequency range of 50 kHz-5 MHz. Experimental results confirmed that the N-ss, R-s and interfacial layer are important parameters that influence electrical characteristics of SBD. (C) 2011 Elsevier B. V. All rights reserved.

TiO2 thin films were deposited on polycrystalline n-type Si substrate using DC magnetron sputtering system. To improve the crystal quality, thermal annealing (TA) process was done at 700 degrees C and 900 degrees C. The effect of TA on the structural properties was investigated using high resolution X-ray diffraction (HRXRD). It was observed that the phase transition from amorphous phase to anatase and rutile phases occurs at 700 degrees C and 900 degrees C, respectively. Au/TiO2/n-Si structures were also fabricated for the investigation of TA on the main electrical parameters, such as ideality factor (n), barrier height (Phi B), series resistance (R-s), shunt resistance (R-sh) and interface states (N-ss). The current-voltage (I-V) and capacitance-voltage (C-V) characteristics have been investigated at room temperature and results have been compared with each other. The electrical characteristics showed that TA strongly affects the main electrical parameters. The rectifying ratio of Au/n-Si structures with anatase phase TiO2 was to be 140 while the rutile phase was to be 8864. The leakage current was also found to be very sensitive to the annealing temperature, and also the magnitude of the leakage current for rutile phase is 15 times lower than the anatase phase's. In addition, the energy distribution profile of N-ss of the structures was obtained from the forward bias I-V data by taking the bias dependence of the effective barrier height (Phi(e)) into account. For both of the samples, the value of N-ss decreases with TA. Similarly, the values of R-s and R-sh of the structures obtained from the forward bias I-V data were found as 209 Omega and 42 k Omega for the anatase and 59 Omega and 598 k Omega for the rutile phase. These results show that the performance of the Au/TiO2/n-Si structure improved with thermal annealing. (C) 2010 Elsevier B.V. All rights reserved.

In this phase II study, activity and safety of neoadjuvant regional hyperthermia (RHT) combined with chemotherapy was investigated in 59 patients with primary advanced or recurrent high-risk soft-tissue sarcoma (STS). Patients received four EIA cycles consisting of etoposide, ifosfamide and doxorubicin combined with RHT followed by surgical resection and adjuvant treatment. The overall objective response (OR) rate was 17%, with one complete (2%) and eight partial (15%) responses. In addition, 13 minor reponses (25%) were seen. At time of surgery, complete necrosis (pCR) occurred in 6 patients and >75% necrosis (favourable histological response (FHR)) in 12 patients. At the completion of protocol treatment, 36 patients were rendered disease-free which was significantly associated with the initial radiographic and/or pathological tumour response ( P =0.004). Treatment-related toxicity was acceptable overall. At a medium follow-up of 82 months, local treatment failure occurred in 33 patients, median overall survival (OS) was 52 months, and the 5-year survival rate was 49% (95% confidence interval (CI): 36–61%). OS which did not differ for extremity versus non-extremity STS ( P =0.21) was better for patients responding to EIA combined with RHT ( P

Öz bulunamadı.

Philadelphia chromosome-positive acute lymphoblastic leukaemia (ALL) is most common in adults and is associated with poor prognosis. Since karyotypic identification of the Philadelphia translocation has been hampered by technical difficulties, we used the polymerase chain reaction (PCR) to look for the BCR-ABL rearrangement in stored samples from a selected group of 314 German ALL patients. BCR-ABL transcripts were found in 77 of 179 adults and were restricted to those with B-precursor leukaemias. 55% of adult common ALL patients had BCR-ABL and its presence correlated with poor overall survival and remission duration. Of 135 children with common ALL, 5 (6%) primary cases and 8 (17%) with recurrent neoplasias were PCR-positive. We recommend prospective evaluation of BCR-ABL analysis with PCR in patients with a B-precursor leukaemia.

The present paper reports on the development of a numerical model for LPG tanks engulfed in flames, A detailed description of the required phenomenological relations and assumptions is also given. The model uses a lumped approach for the lading with two major control volumes linked by the evaporation of a stratified interface. Comparison between the model's predictions and field test data show close agreement.