Abstract: A heterojunction acoustic charge transport device (HACT) having a charge transport channel 39 which is sandwiched between upper and lower charge confinement layers, 14,20, has the charge transport channel 39 made of a Strained Layer Superlattice (SLS) comprising alternating deep-well semiconductor layers 40, that provide a deep quantum well depth, and strain relief layers 42 that provide strain relief to prevent dislocations from occurring due to lattice mismatches between the InGaAs layers within the channel 39 and the charge confinement layers 14,20, thereby allowing the overall thickness of the channel 39 to be at least as wide as conventional HACT devices that use a GaAs channel. The strain relief layers 42 may be narrowly sized to allow tunneling of electrons across the entire channel 39 thereby allowing the charge to move as a single group, or alternatively, widely sized to provide separate isolated channels thereby allowing the charge to move in separate groups.

Abstract: A heterojunction acoustic charge transport (HACT) device having a charge transport layer 16 surrounded by upper and lower charge confinement layers 14,30, respectively, and having a cap layer 36 at the outer surface, above the upper confinement layer 30, is provided with a P-N junction to minimize the effects of surface states. An intermediate layer 34 is disposed between the cap layer 36 and upper charge confinement layer 30. The upper confinement layer 30 and intermediate layer 34 are doped with opposite polarities to provide a P-N junction which creates a built-in electric field having sufficient strength to keep mobile charge carriers, transported by a SAW along the charge transport channel, from being trapped by or recombined with surface states at the external interface of the cap layer 36. Alternatively, the intermediate layer is not present and a cap layer 42 is doped to provide one side of the P-N junction.

Abstract: A HACT device which propagates charge packets 21 along a charge transport channel 17 by a surface acoustic wave (SAW) 14 is provided with an interdigital electrode grid 30 disposed on the upper surface of the HACT, near the charge transport channel 17, having electrodes 30 spaced a distance of one-half wavelength of the SAW. A hold voltage Vh is applied across alternating electrodes to store (i.e., stop and hold) each charge packet. When a charge packet is to be released, the hold voltage Vh is removed and the electrodes 30 are shorted together or alternatively connected through a maximum allowable impedance, thereby allowing each charge packet 21 to be stored and released by the device without having the electrodes 30 absorb the SAW electric fields. Because the electrodes 30 are spaced one-half a SAW wavelength apart, the HACT memory can store each and every charge packet 21, thereby providing a Nyquist bandwidth device.

Abstract: A sampling device operating as a buffer between a first data signal and a relatively slow processing device accepts the input signal and stores samples of it on a SAW traveling past an input electrode. A blocking potential is applied to a set of electrodes to store a set of charge packets with the SAW device. Packets are consecutively released at a slower rate accommodated to the needs of the next processing unit in line, to read out the sampled signal at a modified rate for intentional distortion of the input signal, for slowing the output stored signal rate, or for time reversal of the signal.

Abstract: A high speed analog to digital converter system employs a set of ACT devices in parallel to buffer a high speed data sampling rate to the processing rate of the analog to digital converters employed. Vernier control of phase between individual devices is maintained by controlling the speed of propagation of the SAW wave by illumination of the substrate in response to a phase comparison between the SAW and a reference signal.

Abstract: A one-dimensional or two-dimensional transmission mode spatial light modulator (SLM) includes one or more heterojunction acoustic charge transport (HACT) channels 18 with surrounding layers 16,20 vertically adjacent to a multiple quantum well (MQW) region 14, grown above a thick semiconductor substrate 10 thick enough to allow a surface acoustic wave (SAW) to propagate and transparent to the incident light 40. The SAW is injected by a transducer 24, charge is carried to and from the HACT channel 18 by electrodes 32,34,36, and light 40 is applied to a surface 44 perpendicular to the MQW region 14. Each charge packet 19 in the HACT channel 18 invokes an electric field 52 within the MQW region 14 which determines the optical absorption and index-of-refraction thereof, thereby determining the intensity and/or phase of each output light beam 45. Light modulation is achieved by modulating the amount of charge injected.

Abstract: A one-dimensional or two-dimensional transmission mode spatial light modulator (SLM) includes two different mediums, one medium being a semiconductor comprising one or more heterojunction acoustic charge transport (HACT) channels 28 with surrounding layers 26, 30 vertically adjacent to a multiple quantum well (MQW) region 22, and the other being a transparent piezoelectric insulating substrate 10 thick enough to allow a surface acoustic wave (SAW) 13 to propagate therein. The SAW 13 is launched in the substrate 10 by a transducer 12 and generates electric fields which propagate the charge along the HACT channel 28 in the semiconductor medium 18. Electrodes 32, 34, 36 carry charge to and from the HACT channel 28, and light 40 is applied to a surface 44 perpendicular to the MQW region 22.

Abstract: A high speed analog to digital converter system employs a set of ACT/HACT devices in parallel to buffer a high speed data sampling rate to the processing rate of the analog to digital converters employed. Calibration is maintained by periodic comparison of the results of the same input data.

Abstract: A device having at least two channels for holding electron packets receives serial data in a first channel. A blocking potential is applied to a set of electrodes to store a set of charge packets with the device. Packets are transferred to the other channel, manipulated and released to travel to an output port. Manipulation operations include arithmetic operations, logic operations, multiplexing and demultiplexing.

Abstract: The surface acoustic wave device which generates two coherent signals from a single input. The inventive device has three interdigital transducers (IDT) spaced upon a single piezoelectric substrate. The central IDT has three sets of interdigital fingers.A power splitter and an amplifier are connected between the central IDT and one of the other IDT's to form a recirculation loop. An input signal burst applied to the central IDT produces two coherent outputs at the remaining IDT and the power splitter.

Abstract: A large bandwidth, tapped delay line (TDL) surface acoustic wave (SAW) adaptive processor arrangement, for processing a plurality of array values employed as tap weights in the TDL device. The weight quantities may be real or complex. In the complex case, no phase quadrature combiner is required as a result of the technique of offsetting the real and imaginary delay lines, or offset launching of the frequency waveforms to be mixed.

Abstract: A large bandwidth, tapped delay line (TDL) surface acoustic wave (SAW) adaptive processor arrangement, for processing a plurality of array values employed as tap weights in the TDL device. The weight quantities may be real or complex. In the complex case, no phase quadrature combiner is required as a result of the technique of offsetting the real and imaginary delay lines, or offset launching of the frequency waveforms to be mixed.

Abstract: Low reflectivity electrodes (2-4) are formed within recesses extending from a major surface of a semiconductive and piezoelectric substrate (1) (such as gallium arsenide) so as to reduce SAW reflectivity from the electrodes.

Abstract: Low reflectivity electrodes (2, 7) are provided on semiconductive and piezoelectric substrates (1, 6) including a layer (3, 9) of gold-germanium mixture and a layer (5, 8) of raw gold, or only a gold-germanium mixture (10), the total germanium content of the electrode comprising approximately 2%-3% of the total gold and germanium content of the electrode, and the thickness of the electrode being on the order of 1% of the acoustic wavelength.

Abstract: Low cost, easily reproducible piezoelectric deflector (8) operable with low voltages is achieved by providing an interdigital electrode configuration (12, 13) on a surface of piezoelectric material (10) having alternate sites (15, 16) with different piezoelectric response. A preferred embodiment polarizes the sites oppositely in a piezoelectric ceramic substrate (10). Alternate sites in piezoelectric crystals may be removed or have their piezoelectricity substantially reduced. Differential devices (8a, 8b) employ electrodes on both surfaces of the substrate, with a site at one surface being poled oppositely to an adjacent site at the other surface (FIG. 3) or with adjacent sites at both surfaces poled alike, and signal voltages applied oppositely (FIG. 4).

Abstract: Acoustic Wave Devices comprise lithium niobate substrates 6, 22 having the principal plane cut at zero degrees and 128.degree., respectively, with respect to the Y crystallographic axis thereof, propagating in the X direction, with amorphous silicon dioxide surface layers of 0.42 and 1.24 wavelengths, respectively.

Abstract: A plurality of thin pressure sensors are made by processing a first large wafer (20, 110) to provide a plurality of electronic devices (28, 122, 124, 125) having a characteristic which varies inversely with strain, and processing a second wafer (40) to provide a plurality of cavities (46) each registered on the second wafer so as to be registerable with a corresponding device on the first wafer. The wafers (20, 40, 110) have thick undoped silicon substrates (21, 41, 114) which are utilized as handles or carriers during the processing, and are stripped off by etching to a highly doped boron etch stop layer (22, 42, 112) when the processing has proceeded to a point where the need therefore has been satisfied. The first wafers (20, 110) are provided with a suitable pattern of borosilicate glass (except in the region where the pressure sensors are formed) so that the two wafers may be joined by a field assisted bonding at a suitable temperature in a vacuum.

Abstract: A plurality of thin pressure sensors are made by processing a first large wafer (20, 110) to provide a plurality of electronic devices (28, 122, 124, 125) having a characteristic which varies inversely with strain, and processing a second wafer (40) to provide a plurality of cavities (46) each registered on the second wafer so as to be registerable with a corresponding device on the first wafer. The wafers (20, 40, 110) have thick undoped silicon substrates (21, 41, 114) which are utilized as handles or carriers during the processing, and are stripped off by etching to a highly doped boron etch stop layer (22, 42, 112) when the processing has proceeded to a point where the need therefore has been satisfied. The first wafers (20, 110) are provided with a suitable pattern of borosilicate glass (except in the region where the pressure sensors are formed) so that the two wafers may be joined by a field assisted bonding at a suitable temperature in a vacuum.

Abstract: A surface acoustic wave resonator formed on a semiconductive piezoelectric substrate (9) has arrays (10, 11) of reflector elements forming rectifying junctions with the substrate, a voltage is impressed between the arrays and related ohmic ground contacts (12, 13) for controlling the carrier concentration beneath the arrays so as to vary the acoustic velocity therebeneath, thereby to tune the resonator. The resonator may include two acoustoelectric transducers (16, 17) for connection with an amplifier in an oscillator loop, or may have but a single acoustoelectric transducer (20) for interconnection between the elements of an oscillator circuit (21).

Abstract: Temperature compensation is provided to a surface acoustic wave device including acoustoelectric transducers (12, 14) formed on a surface of a gallium arsenide substrate (10), by a composite layer including silicon dioxide (18, 26) and a mass loading metal (20, 24), which may be gold, titanium and gold, or other metals having Rayleigh wave velocities lower than that of gallium arsenide, such as silver and platinum.