The Influence of Excess Nitrogen, on the Electrical Properties of the 4H-SiC/SiO2 Interface

2011 ◽  
Vol 679-680 ◽  
pp. 326-329
Author(s):  
Ioana Pintilie ◽  
Francesco Moscatelli ◽  
Roberta Nipoti ◽  
Antonella Poggi ◽  
Sandro Solmi ◽  
...  
Keyword(s):  
Electrical Properties ◽  
High Frequency ◽  
Close Agreement ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Mos Capacitors ◽  
Virgin Sample ◽  
Capacitance Voltage ◽  
Different Temperatures ◽  
Implantation Process

The effect of nitrogen (N) introduced by ion implantation at the SiO2/4H-SiC interface on the capacitance of the MOS capacitors is investigated. The Thermal Dielectric Relaxation Current (TDRC) technique and Capacitance-Voltage (C-V) measurements performed at different temperatures and probe frequencies on an N implanted sample and on a virgin sample were employed for this purpose. There are three types of defects located at or near the interface, Dit, NIToxfast and NIToxslow that can be distinguished. Only Dit and NIToxfast respond to the a.c. small, high frequency signal at temperatures above 150K. The separation of Dit from the NIToxfast states have enabled us to study the influence of the excess of interfacial Nitrogen on each of the mentioned defects. It has been found that the N-implantation process fully suppresses the formation of NIToxfast and partially NIToxslow and Dit. Theoretical C-V characteristics were computed, based on the defect distributions determined by TDRC, and compared with the experimental ones showing a close agreement.

Thick Oxide Layers on N and P SiC Wafers by a Depo-Conversion Technique

1999 ◽  
Vol 572 ◽  
Author(s):  
Q. Zhang ◽  
V. Madangarli ◽  
I. Khlebnikov ◽  
S. Soloviev ◽  
T. S. Sudarshan
Keyword(s):  
Electrical Properties ◽  
Effective Charge ◽  
High Frequency ◽  
Breakdown Field ◽  
Mos Capacitors ◽  
Mos Capacitor ◽  
Oxide Layers ◽  
Oxide Breakdown ◽  
Thermal Oxide ◽  
Capacitance Voltage

ABSTRACTThe electrical properties of thick oxide layers on n and p-type 6H-SiC obtained by a depoconversion technique are presented. High frequency capacitance-voltage measurements on MOS capacitors with a ∼ 3000 Å thick oxide indicates an effective charge density comparable to that of MOS capacitors with thermal oxide. The breakdown field of the depo-converted oxide obtained using a ramp response technique indicates a good quality oxide with average values in excess of 6 MV/cm on p-type SiC and 9 MV/cm on n-type SiC. The oxide breakdown field was observed to decrease with increase in MOS capacitor diameter.

Dither in a rolling airframe flight vehicle with a two-position actuator: An amplitude distribution approach

2016 ◽  
Vol 39 (8) ◽  
pp. 1205-1215 ◽  
Author(s):  
Bahram Mohammadi ◽  
Mohammad Reza Arvan ◽  
Yousof Koohmaskan
Keyword(s):  
High Frequency ◽  
Degrees Of Freedom ◽  
Coupling Effect ◽  
Cross Coupling ◽  
Amplitude Distribution ◽  
Feedback System ◽  
Flight Vehicle ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Minimal Error

Rolling airframe manoeuvring is a type of manoeuvre in which the missile provides continuous roll during flight. Cross-coupling between the angle of attack and sideslip in rolling airframe missiles (RAMs) yields a coning motion around the flight path. As the pitch and yaw cross-coupling effect decreases, the radius of this coning motion decreases and the accuracy of the control system increases. Two-position (on–off) actuators are used in most RAMs. The presence of a two-position actuator in a feedback system makes its characteristics non-linear. A high-frequency signal so-called dither is applied to compensate for the non-linearity effect of the actuator characteristic in the feedback system and to stabilize the coning motion. The amplitude distribution function (ADF) method in dither analysis shows that the smoothed non-linearity characteristic can be computed as the convolution of the original non-linearity and the ADF of the dither signal. According to the four-degrees-of-freedom (4-DOF) equations of RAMs in a non-rolling frame and regarding various dither signals through the ADF approach on a two-position actuator, an analytical condition for dither amplitude in coning motion stability of RAMs is derived. It was shown that the triangular signal with specified amplitude and high enough frequency led to a smoother response of two-position actuators. Finally, by applying beam-riding guidance to a RAM, the performance of dithers for decreasing the distance of the missile from the centre of the beam is validated through simulations. It is illustrated that applying the triangular dither resulted in minimal error.

scholarly journals An Investigation into Error Source Identification of Machine Tools Based on Time-Frequency Feature Extraction

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Dongju Chen ◽  
Shuai Zhou ◽  
Lihua Dong ◽  
Jinwei Fan
Keyword(s):  
Machine Tool ◽  
Frequency Domain ◽  
Surface Topography ◽  
High Frequency ◽  
Low Frequency ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Time Frequency ◽  
Cross Correlation Analysis ◽  
Correlation Analysis Method

This paper presents a new identification method to identify the main errors of the machine tool in time-frequency domain. The low- and high-frequency signals of the workpiece surface are decomposed based on the Daubechies wavelet transform. With power spectral density analysis, the main features of the high-frequency signal corresponding to the imbalance of the spindle system are extracted from the surface topography of the workpiece in the frequency domain. With the cross-correlation analysis method, the relationship between the guideway error of the machine tool and the low-frequency signal of the surface topography is calculated in the time domain.

Magnet Temperature Estimation in Surface PM Machines Using High-Frequency Signal Injection

2010 ◽  
Vol 46 (4) ◽  
pp. 1468-1475 ◽  
Author(s):  
David Díaz Reigosa ◽  
Fernando Briz ◽  
Pablo García ◽  
Juan Manuel Guerrero ◽  
Michael W Degner
Keyword(s):  
High Frequency ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Temperature Estimation ◽  
Signal Injection
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