Abstract: A memory device, a programmable insulator-semiconductor bipolar transistor (PISBT) and a method for measuring a temperature of a filament, the method may include: providing base voltages of different values to a base of the PISBT; obtaining measurement results by measuring a minority carrier current that flows from a collector of the PISBT in response to the providing of the base voltages of the different values; and calculating the temperature of the filament, based upon the measurement results; wherein the filament is formed in a variable resistance layer of the PISBT when the PISBT is programmed to a certain value out of multiple programmable values, wherein the filament facilitates a flow of minority carriers from an emitter of the PISBT.

Abstract: A heterojunction bipolar transistor (HBT) having an emitter structure capable of reducing the current crowding effect and preventing thermal instabilities is disclosed, wherein a negative differential resistance. (NDR) element is added to the layer structure of the conventional emitter. In accordance with the invention, the NDR element can be implemented, for example, by a Resonant Tunnel Diode (RTD) or an Esaki Diode structure. The NDR element is designed to limit the tunneling current to the maximal emitter current density required for safe transistor operation, thereby also reducing the current crowding effect.

Abstract: An optical apparatus and method for measuring the diffusion length in an insulating photoconductor or a semiconductor sample material, that includes a source of coherent light; means for splitting the light source and providing transmitted and reflected beams each having a variable light intensity, one of the transmitted and reflected beams being incident as a background beam at a location on the sample material, means for directing the other of the transmitted and reflected beams so as to be incident at the location as a probe beam, the directing apparatus establishing a predetermined angle between the background and probe beams at the location, polarizing means disposed in the path of the background beam and having one of two predetermined orientations corresponding to polarized and non-polarized states of the beam passing therethrough, means disposed in the path of the probe beam for periodically blocking the passage thereof; and means for measuring changes in the periodic photocurrent supplied by a power