G.W. Taylor

A new double‐heterostructure optoelectronic switching device using molecular‐beam epitaxy

Two‐terminal switching action is observed in a new optoelectronic device structure. The device has a high‐impedance state without light emission and a low‐impedance state characterized by strong spontaneous emission. The transition from either state to the other may be induced by the appropriate optical or electrical input. It is clear that with the appropriate optical cavity construction the switching device will operate as a laser in the on state rather than in the spontaneous mode reported here. In principle, the device offers large digital optical gain determined by its optical sensitivity and its maximum output power.

The bipolar inversion channel field-effect transistor (BICFET)—A new field-effect solid-state device: Theory and structures

A new solid-state field-effect bipolar device designated the BICFET for bipolar inversion channel field-effect transistor is proposed. The device, which is bipolar in nature and relies upon the field-effect inducement of an inversion layer, that corresponds to the conventional neutral base of a bipolar transistor, features potentially very high current gain (105), very high current operation (106A/cm2) and thus high transconductance (4 × 107S/cm2) and low input capacitance. The BICFET has three terminals: a metallic emitter which makes ohmic contact to a semi-insulator (wide bandgap semiconductor); a source terminal which contacts an inversion layer formed at the interface between the semi-insulator and the semiconductor depletion region; and a collector which is the semiconductor bulk. An important feature of this bipolar device is the absence of the base layer and all of its associated problems. The principle of operation is based on controlling the flow of majority carriers through the semi-insulating region to the collector by the biasing action of charge in the inversion channel. A significant advantage of the BICFET structure is that it is not subject to the scaling limitations due to punchthrough as in the MOS or junction bipolar transistor. The problem of threshold control in the MOS transistor is avoided, so the requirement of very shallow junctions may be relaxed.

Ledistor—a three‐terminal double heterostructure optoelectronic switch

A three‐terminal double heterostructure optoelectronic switching (DOES) device is demonstrated. By making ohmic contact to the active region of the DOES device the switching characteristic may be controlled up to the punchthrough limit. The device emits light in the on state only and various combinations of voltage and optical input power can be used to switch the device.

Optically induced switching in a p‐channel double heterostructure optoelectronic switch

The switching time of a double heterostructure optoelectronic switch is investigated using an optical input. A switch‐on time of 5–10 ps is obtained using a discrete microwave package. The fall time of 10 ns is limited almost totally by the parasitic capacitance of the package. The switching operation shows the unique ability to turn on and off with the incident optical signal.

Theory of operation of the quantum‐well injection laser without k selection

The quantum‐well laser is described in terms of the appropriate quasi‐Fermi levels and Einstein coefficient for stimulated emission. Emission frequencies, thresholds currents temperature dependencies, and linewidths are determined as a function of the quantum‐well parameters, the photon lifetime, the temperature, and the emission coefficient. Correlation with existing data is demonstrated.

Double-heterostructure optoelectronic switch as a single quantum well laser

The double‐heterostructure optoelectronic switch (DOES) is demonstrated as an N‐channel, single quantum well, graded index laser. As a broad‐area device, the DOES exhibits excellent electrical switching characteristics of 12 V and 0.04 A cm−2 at the switching condition and 1.8 V and 3.3 A cm−2 at the holding condition with 8.4×10−4 Ω cm2 on state resistance. As a laser, threshold current densities down to 580 A/cm2, loss of 11 cm−1, slope efficiency of 0.35 mA/mW, and total power conversion efficiency of 45% were obtained.

Optoelectronic dynamic random access memory cell utilizing a three-terminal N-channel self-aligned double-heterostructure optoelectronic switch

The double‐heterostructure optoelectronic switch is demonstrated as a novel dynamic random access optoelectronic memory cell in an N‐channel self‐aligned three‐terminal configuration. The cell employs a single polarity of bias and XY selectivity using the inversion channel contact and the optical input/output port. The switching powers, delays, and refresh capability offer the promise for large‐scale integrated circuits.

Experimental realization of an n‐channel double heterostructure optoelectronic switch

An n‐channel double heterostructure optoelectronic switch has been demonstrated. As in the case of the p‐channel device, there is a high impedance state without light emission and a low impedance state with strong spontaneous emission. The states are changed by optical or electrical signals and a digital optical gain of 14 is observed. The switching voltage is higher and the holding current is lower than in the p‐channel case.

A device model for buried-channel CCD's and MOSFET's with Gaussian impurity profiles

Analytical forms are developed for the buried-channel CCD and its counterpart the buried-channel MOSFET having Gaussian impurity charge profiles. The results are able to describe all important potentials, charges, distances, and currents in terms of the profile structural parameters. The model will be quite useful in the design of buried-channel circuits for VLSI applications where it is expected that highly nonlinear profiles will be obtained by the use of very shallow ion implants and minimal high-temperature processing.

Determination of the switching condition in the quantum-well double-heterostructure optoelectronic switch (DOES)

The switching mechanism in the GaAs/AlGaAs double-heterostructure optoelectronic switching device (DOES) is investigated in the context of the single-quantum-well graded index laser structure. A new charge conservation approach is introduced to explain the switching mechanism responsible for the thyristor-like behavior. Simple results are obtained for design purposes for currents, voltages, charges, and electric fields at the switching conditions. Switching energies are found to be on the order of 0.1-0.5 fJ/ mu m/sup 2/. >