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The dependences of the common-emitter current gain [beta.sub.CE] on the collector current [I.sub.C] are measured at elevated temperatures for 1-kV 30-A 4H-SiC epitaxial emitter n-p-n bipolar junction transistors (BJTs). The minority carrier lifetimes and surface recombination velocity are obtained by the means of the simulation of a model that takes into account the main processes affecting the current gain.

A general estimation can be made of the carrier lifetime in the base, in high-voltage SiC diodes, using steady-state current-voltage characteristics at high injection levels. The transient time of the switch-on process can also be used for an estimate. Given an estimate of lifetime magnitude, the injection efficiency of the emitter can be evaluated.

A new study investigates the temperature dependencies of low-frequency noise in heterostructure field-effect transistors.

Research shows that the critical charge density of 4H-SiC thyristors is two times ten (super 15) centimeters (super -3) and ten (super 14) centimeters (super -3) at a forward voltage of five and 100 volts and 560 degrees kelvin. Experiments using maximum voltage ramp determine anode current density levels of between three and 7.5 times ten (super 2) angstroms per centimeter squared.

The turn-on performance of 4H-Silicon Carbide (SiC) npnp thyristors are influenced by factors such as critical charge density, residual voltage, spread velocity and the rise time constant of the anode current. A comparative analysis involving similar silicon and Gallium Arsenide thyristors revealed the superiority of SIC in terms of pulsed turn-on performance and rise time.

AlGaN thin films and Schottky barrier Al0.4Ga0.6N diodes exhibit generation-recombination (GR) noise with activation energies of 0.8 - 1 eV. GR noise in AlGaN/GaN Heterostructure Field Effect transistors (HFETs) corresponds to activation energies in the range from 1 - 3 meV to 1 eV. No GR noise is observed in thin doped GaN films and GaN MESFETs. GR noise with the largest reported activation energy of 1.6 eV was measured in AlGaN/InGaN/GaN Double Heterostructure Field Effect Transistors (DHFETs). Local levels responsible for the GR noise in HFETs and DHFETs might be located in AlGaN barrier layers. [ABSTRACT FROM AUTHOR]