Experimental observation of spatial structures due to current filament formation in silicon pin diodes

To study the electrical current density and the potential distribution inS-shaped negative differential conductivity materials, a theoretical model is developed which is based upon the introduction of an interface dividing the material into two parts of different electrical behaviour. This interface model which leads to a set of coupled nonlinear evolution equations for two physical quantities at the boundary layer is that of an activator inhibitor type as used to describe self-controlled processes in chemistry and biology. Numerical calculations of inhomogeneous stationary states are presented for various parameters. From the numerical calculations these states are found to be stable with respect to small variations of the parameters (structure-stability) and fluctuations of the dependent variables. The model is confirmed by experiments performed on silicon pin diodes. The measured potential distribution is in a good qualitative agreement with the theoretical calculations.

Pattern formation in S-shaped negative differential conductivity material

This paper gives an overview of the physics and electrical characteristics of irradiation-induced defects in silicon created by electrons, protons, and helium ions. The parameters of the traps usable as recombination centers or causing doping and discharging effects are described quantitatively, including temperature dependence and injection level dependence. The influence of recombination centers on the electric characteristics of power devices is discussed, especially with respect to applications for medium-voltage and high-voltage power devices.

Irradiation-Induced Deep Levels in Silicon for Power Device Tailoring

Observation of spatio-temporal structures due to current filaments in Si pin diodes

I–V characteristics of single crystal vanadium dioxide has been measured using a constant current source in the ambient temperature region 220–325°K. The temperature of the crystal surface has also been measured. It is observed that the switching voltage ( V th ) increases but the current at switching ( I th ) decreases with decreasing temperature, giving a temperature independent threshold power ( V th × I th ). At switching, the temperature of the crystal surface increases only by 3–6°K above ambient for different ambient temperatures. These results can be qualitatively explained by assuming that a filament (channel) is formed before switching. The switching occurs when the temperature of this filament of finite width approaches the semiconductor-metal transition temperature. The initial width of the channel at switching decreases with decreasing temperature and at a given ambient temperature the channel width increases with increasing current in the post breakdown region.

Electrical switching in single crystal VO2

Calculations have been made of dc I‐V characteristics of long p+‐i‐n+ diodes with deep levels showing a negative differential resistance region. The influence of the recombination center data, especially of the capture coefficients of both electrons and holes, cn and c−p, is discussed. The calculations show that cn only influences the high injection regime and the minimum voltage, whereas c−p only influences the prebreakdown region and the breakdown voltage; thus a new method arises to determine cn and c−p in the same sample. These results are confirmed in silicon p+‐i‐n+ diodes with the gold acceptor acting as recombination center. Theory and experimental results are in complete agreement for cn=3.2×10−8 cm3 s−1 and c−p=1×10−7 cm3 s−1. Finally, these values are compared with those given in the literature.

I. Dudeck

Papers

The influence of recombination center data on the I‐V characteristics of silicon p+‐i‐n+ diodes