60 research outputs found
A Study of a-Sic/C-Si(n) Isotype Heterojunctions
In the present work a study of the electrical properties of heterojunctions between rf sputtered amorphous
silicon carbide (a-SiC) thin films and n-type crystalline silicon (c-Si) substrates is reported. The
current-voltage (I-V) and capacitance-voltage (C-V) characteristics, as well as the temperature dependence
of the current of a-SiC/c-Si(n) heterojunctions were measured. The I-V characteristics of a-SiC/
c-Si(n) heterojunctions exhibit poor rectification properties, with a high reverse current, at higher
temperatures (T > 250K), whereas good rectification properties are obtained at lower temperatures (T
< 250K). It was found that the a-SiC/c-Si(n) heterojunctions are isotype, suggesting that-the conductivity
of a-SiC is n-type. The temperature dependence of the current (from 185K to 320K) showed that the
majority carriers of c-Si(n) (i.e. electrons) are transported from c-Si(n) to a-SiC mainly by the thermionic
emission mechanism, or by the drift-diffusion mechanism. From C-V measurements of a-SiC/c-Si(n)
heterojunctions the electron affinity of a-SiC was found to be X1 = 4.20 ± 0.04 eV. Finally, the a-SiC/
c-Si(n) isotype heterojunctions are expected to be interesting devices as infrare
New High-Speed a-Si/c-Si- and a-SiC/c-Si-Based Switches
The electrical and optical characteristics of the new high-speed Al/a-Si/c-Si(p)/c-Si(n+)/Al and Al/a-
SiC/c-Si(p)/c-Si(n+)/Al optically controlled switches are presented in this paper. These switches exhibit
the lowest ever reported values of rise and fall times, for this kind of switches, of about 3ns. They also
exhibit a temperature and light reversibly controlled forward breakover voltage (VBF), together with
high values of light triggering sensitivity
Schottky barrier heights at polar metal/semiconductor interfaces
Using a first-principle pseudopotential approach, we have investigated the
Schottky barrier heights of abrupt Al/Ge, Al/GaAs, Al/AlAs, and Al/ZnSe (100)
junctions, and their dependence on the semiconductor chemical composition and
surface termination. A model based on linear-response theory is developed,
which provides a simple, yet accurate description of the barrier-height
variations with the chemical composition of the semiconductor. The larger
barrier values found for the anion- than for the cation-terminated surfaces are
explained in terms of the screened charge of the polar semiconductor surface
and its image charge at the metal surface. Atomic scale computations show how
the classical image charge concept, valid for charges placed at large distances
from the metal, extends to distances shorter than the decay length of the
metal-induced-gap states.Comment: REVTeX 4, 11 pages, 6 EPS figure
The a-SiC/c-Si(n) Isotype Heterojunction as a High Sensitivity Temperature Sensor
The a-SiC/c-Si(n) isotype heterojunction has been studied
as a temperature sensor by measuring its reverse current-voltage
(IR−V)
and reverse voltage-temperature (V-T)
characteristics, as well as its reverse current temperature
dependence. The IR−V
characteristics exhibit an almost constant
current, whereas the reverse current IR depends strongly on T
(from 230 K up to 320K). The V-T characteristics, at
different reverse currents, reveal a highly temperature sensitive
behavior for the a-SiC/c-Si(n) junction. The measured
values of temperature sensitivity (Δ V/ΔT)max was found to be
(≅−2.5 V/K) in the moderate temperature range, which are
much higher than those obtained with bulk semiconductor
temperature sensors. The high sensitivity-temperature- range of
the a-SiC/c-Si(n) heterojunctions can be controlled
electrically within the regim of values from 230 K up to 320 K.
Finally, the high sensitivity of these devices, in conjunction
with the fact that a-SiC films can be used as an add-on to the
existing Si technology, emerge new possibilities to the
fabrication of high sensitivity temperature microsensors
A TCAD tool for the simulation of the CVD process based on cellular automata
The development of next-generation VLSI circuits with deep submicron technologies demands fundamental understanding of the wafer surface reaction kinetics. Technology cornputer-aided design (TCAD) is essential for modeling real fabrication processes accurately, and allowing predictive simulation during technology research and development. This paper describes a two-dimensional Chemical Vapor Deposition (CVD) process TCAD system based on cellular automata (CAs). The proposed TCAD system can handle the complicated boundary and initial conditions imposed by defects and provide SEM-like cross sectional views. The simulated profiles obtained are in very good agreement with experimental and simulation results found in the literature. Furthermore, a user-friendly interface that enables easy and effective interaction between the user and the TCAD system has been developed
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