Abstract: Low cost millimeter wave imagers using two-dimensional focal plane arrays based on backward tunneling diode (BTD) detectors. Two-dimensional focal arrays of BTD detectors are used as focal plane arrays in imagers. High responsivity of BTD detectors near zero bias results in low noise detectors that alleviate the need for expensive and heat generating low noise amplifiers or Dicke switches in the imager. BTD detectors are installed on a printed circuit board using flip chip packaging technology and horn antennas direct the waves toward the flip chip including the BTD detectors. The assembly of the horn antennas, flip chips, printed circuit board substrate, and interconnects together work as an imaging sensor. Corrugated surfaces of the components prevent re-radiation of the incident waves.

Abstract: A semiconductor device exhibiting interband tunneling with a first layer with a first conduction band edge with an energy above a first valence band edge, with the difference a first band-gap. A second layer with second conduction band edge with an energy above a second valence band edge, with the difference a second band-gap, and the second layer formed permitting electron carrier tunneling transport. The second layer is between the first and a third layer, with the difference between the third valence band edge and the third conduction band edge a third band-gap. A Fermi level is nearer the first conduction band edge than the first valence band edge. The second valence band edge is beneath the first conduction band edge. The second conduction band edge is above the third valence band edge. The Fermi level is nearer the third valence band edge than to the third conduction band edge.

Abstract: Low cost millimeter wave imagers using two-dimensional focal plane arrays based on backward tunneling diode (BTD) detectors. Two-dimensional focal arrays of BTD detectors are used as focal plane arrays in imagers. High responsivity of BTD detectors near zero bias results in low noise detectors that alleviate the need for expensive and heat generating low noise amplifiers or Dicke switches in the imager. BTD detectors are installed on a printed circuit board using flip chip packaging technology and horn antennas direct the waves toward the flip chip including the BTD detectors. The assembly of the horn antennas, flip chips, printed circuit board substrate, and interconnects together work as an imaging sensor. Corrugated surfaces of the components prevent re-radiation of the incident waves.

Abstract: A semiconductor device exhibiting interband tunneling with a first layer with a first conduction band edge with an energy above a first valence band edge, with the difference a first band-gap. A second layer with second conduction band edge with an energy above a second valence band edge, with the difference a second band-gap, and the second layer formed permitting electron carrier tunneling transport. The second layer is between the first and a third layer, with the difference between the third valence band edge and the third conduction band edge a third band-gap. A Fermi level is nearer the first conduction band edge than the first valence band edge. The second valence band edge is beneath the first conduction band edge. The second conduction band edge is above the third valence band edge. The Fermi level is nearer the third valence band edge than to the third conduction band edge.

Abstract: A method of epitaxially growing backward diodes and diodes grown by the method are presented herein. More specifically, the invention utilizes epitaxial-growth techniques such as molecular beam epitaxy in order to produce a thin, highly doped layer at the p-n junction in order to steepen the voltage drop at the junction, and thereby increase the electric field. By tailoring the p and n doping levels as well as adjusting the thin, highly doped layer, backward diodes may be consistently produced and may be tailored in a relatively easy and controllable fashion for a variety of applications. The use of the thin, highly doped layer provided by the present invention is discussed particularly in the context of InGaAs backward diode structures, but may be tailored to many diode types.

Abstract: A tunnel diode has a quantum well having at least one layer of semiconductor material. The tunnel diode also has a pair of injection layers on either side of the quantum well. The injection layers comprise a collector layer and an emitter layer. A barrier layer is positioned between each of the injection layers and the quantum well. The quantum well has an epitaxial relationship with the emitter layer. An amount of one element of the well layer is increased to increase the lattice constant a predetermined amount. The lattice constant may have a reduction in the conduction band energy. A second element is added to the well layer to increase the conduction band energy but not to change the lattice constant. By controlling the composition in this matter, the negative resistance, and thus the effective mass, may be controlled for various diode constructions.

Abstract: A method for producing laterally varying multiple diodes and their device embodiment are presented herein. As demonstrated, multiple resonant tunneling diodes are fabricated together utilizing a single epitaxial structure. Shallow, ion-implanted regions having varying depths, dx, define the collector contacts. Each diode is isolated electrically from the others by methods such as conventional mesa etching into the emitter layer. The varying depths, dx, provide means for varying the peak voltage of each individual diode. The peak voltage strongly depends on the depths, dx, because it comprises a space charge region where the electric field is high, and therefore the voltage drop is high. The invention disclosed herein is useful in applications such as high-speed circuits such as comparators, analog to digital converters, sample and hold circuits, logic devices, and frequency multipliers.

Abstract: A method of epitaxially growing backward diodes and diodes grown by the method are presented herein. More specifically, the invention utilizes epitaxial-growth techniques such as molecular beam epitaxy in order to produce a thin, highly doped layer at the p-n junction in order to steepen the voltage drop at the junction, and thereby increase the electric field. By tailoring the p and n doping levels as well as adjusting the thin, highly doped layer, backward diodes may be consistently produced and may be tailored in a relatively easy and controllable fashion for a variety of applications. The use of the thin, highly doped layer provided by the present invention is discussed particularly in the context of InGaAs backward diode structures, but may be tailored to many diode types.

Abstract: A backward diode including a heterostructure consisting of a first layer of InAs and second layer of GaSb or InGaSb with an interface layer consisting of an aluminum antimonide compound is presented. It is also disclosed that the presence of AlSb in the interface enhances the highly desirable characteristic of nonlinear current-voltage (I-V) curve near zero bias. The backward diode is useful in radio frequency detection and mixing. The interface layer may be one or more layers in thickness, and may also have a continuously graded AlGaSb layer with a varying Al concentration in order to enhance the nonlinear I-V curve characteristic near zero bias.

Abstract: A method of epitaxially growing backward diodes as well as apparatus grown by the method are presented herein. More specifically, the invention utilizes epitaxial-growth techniques such as molecular beam epitaxy in order to produce a thin, highly doped layer at the p-n junction in order to steepen the voltage drop at the junction, and thereby increase the electric field. By tailoring the p and n doping levels as well as adjusting the thin, highly doped layer, backward diodes may be consistently produced and may be tailored in a relatively easy and controllable fashion for a variety of applications. The use of the thin, highly doped layer provided by the present invention is discussed particularly in the context of InGaAs backward diode structures, but may be tailored to many diode types.

Abstract: A tunnel diode has a quantum well having at least one layer of semiconductor material. The tunnel diode also has a pair of injection layers on either side of the quantum well. The injection layers comprise a collector layer and an emitter layer. A barrier layer is positioned between each of the injection layers and the quantum well. The quantum well has an epitaxial relationship with the emitter layer. An amount of one element of the well layer is increased to increase the lattice constant a predetermined amount. The lattice constant may have a reduction in the conduction band energy. A second element is added to the well layer to increase the conduction band energy but not to change the lattice constant. By controlling the composition in this matter, the negative resistance, and thus the effective mass, may be controlled for various diode constructions.

Abstract: A tunnel diode has a quantum well having at least one layer of semiconductor material. The tunnel diode also has a pair of injection layers on either side of the quantum well. The injection layers comprise a collector layer and an emitter layer. A barrier layer is positioned between each of the injection layers and the quantum well. The quantum well has an epitaxial relationship with the emitter layer. An amount of one element of the well layer is increased to increase the lattice constant a predetermined amount. The lattice constant may have a reduction in the conduction band energy. A second element is added to the well layer to increase the conduction band energy but not to change the lattice constant. By controlling the composition in this matter, the negative resistance, and thus the effective mass, may be controlled for various diode constructions.

Abstract: A sample and hold circuit that is coupled to a control voltage source and a signal source has a sampling bridge coupled in series between a first resonant tunneling diode. The bridge comprises a plurality of diodes. The sampling bridge couples an input voltage signal that is to be sampled to a holding capacitor when the sampling bridge is forward biased. The bridge substantially decouples the input voltage signal from the holding capacitor when the sampling bridge diodes are reversed biased. The resonant tunneling diodes when reversed biased allow the bridge to be isolated from the control voltage source to allow the holding capacitor to float at the sampled value of the input voltage.

Abstract: Presented is an integrated asymmetric resonant tunneling diode pair circuit exhibiting current-voltage characteristics providing multistable states which may be tailored for multistable solutions. Also presented are apparatus incorporating the invention therein, for which the invention provides a simple, integrated design that greatly reduces circuit complexity and size. The present invention is useful in all applications utilizing multiple peak characteristics of the current-voltage curve, such as multiple-valued logic analog-to-digital quantizers, frequency multiplication devices, waveform scrambling devices, memory operations, and parity-bit generation, among others.

Abstract: Base contacts are made to one or both barrier layers of a resonant tunneling bipolar transistor, rather than to the quantum well. This is made possible with the use of a type II rather than a type I energy band alignment in the active region.

Abstract: A current-controlled resonant tunneling diode (RTD) having an InAs quantum well, AlGaSb barriers and InAs cladding layers is disclosed. The RTD of this invention displays an S-shaped negative differential resistance in its I-V relationship. As a result, the RTD displays the bistability necessary to greatly enhance the speed of operation of many key electronic components by eliminating the need for large load resistances in the circuit design.

Abstract: A double barrier tunnel diode (10) has a quantum well (12), a pair of electron injection layers (16) on either side of the quantum well (12), and a barrier layer (14) between each of the electron injection layers (16) and the quantum well (12), in a strained biaxial epitaxial relationship with the quantum well (12). The material of the quantum well (12) is chosen such that the biaxial strain is sufficient to reduce the energy of heavy holes in the quantum well (12) to less than the energy of the conduction band minimum energy of the electron injection layers (16). Preferably the quantum well (12) is made of gallium antimonide with from about 1 to about 40 atomic percent arsenic alloyed therein, the electron injection layers (16) are made of indium arsenide, and the barrier layers (14) are made of aluminum antimonide.

Abstract: Various optical modulation systems and methods are disclosed which are based upon modulating the refractive index of a nipi structure. The refractive index modulation is accomplished by applying a controlled voltage differential across the n-doped and p-doped layers of the structure. Staggered contacts to the layers are formed by conductive elements which extend through the structure. One of the elements establishes ohmic contacts with the n layers, and the other with the p-layers. When implemented as an optical spatial phase modulator, one of the nipi contacts is provided as a grid which divides the structure into a matrix of pixel elements, with the other contact comprising separate wires extending through each pixel. A spatial voltage pattern is applied to the pixel wires to inject charge into their corresponding layers, and thereby modulate the refractive indices of the pixels. This imposes a desired spatial phase modulation onto a readout beam transmitted through the nipi structure.

Abstract: A double barrier tunnel diode, wherein a central quantum well is disposed between a pair of barrier layers to form a quantum barrier, the barrier layers having a composition such that a resonance energy level is created in the quantum well layer, and having a thickness sufficiently small that electrons can tunnel through the quantum barrier under an applied voltage. The quantum well and barrier layers are disposed between two electron injection layers having compositions selected so that the conduction band minimum energy for electrons in the injection layers is about that of, but less than, the resonance energy level of the quantum well. Electrons pass through the quantum barrier by tunneling, upon application of a small voltage across the double barrier tunnel diode sufficient to raise electrons near the conduction band minimum energy of the injection layer to the resonance energy level of the quantum well.

Abstract: A resonant quantum well laser incorporates semiconductor barriers on one or both sides of the quantum well to increase the charge density within the quantum well. The composition of the injection layers can be tailored in a manner that the energies of the charge carriers in the injection layers are about that of a resonant energy level for that type of charge carrier in the quantum well. The barrier layers on one or both sides of the quantum well enhance the probability of the charge carrier being in the well for a longer time and travelling a longer distance, increasing the chance of scattering. The charge carriers, electrons or holes, can move from their respective injection layers into nearly identical energy levels within the quantum well, by tunneling through the thin barrier layers. The number of carriers which are available to transfer into the lasting energy level is increased, thereby increasing the efficiency of the laser and lowering its threshold current.