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We describe the development and optical characterization of a planar medium infrared (mid-IR) InSb photodetector on a GaAs substrate technology, capable of integrating MESFETs, to demonstrate a new active pixel device architecture. Our results pave the way for the development of integrated mid-IR focal plane array circuits on a single chip. Device structures with areas down to 0.0016 mm $^{{ {2}}}$ were investigated. By deploying a silicon nitride passivation layer, we were able to reduce leakage current in reverse bias by up to 27% to yield an improved rectifier. Extensive optical characterization was carried out in the near- and mid-IR wavelength range. Responsivities of up to 3.54 A/W and quantum efficiency values above unity were obtained in the near-IR range as a consequence of illumination above the bandgap causing impact ionization. In the mid-IR range, responsivities of up to 0.97 A/W were observed. The bandwidth of the devices proved compatible with video-rate standard sampling rates. [ABSTRACT FROM PUBLISHER] more...

Medium wavelength infrared (MWIR) detectors are of increasing importance in defense, security, commercial, and environmental applications. Enhanced integration will lead to greater resolution and lower cost focal plane arrays (FPAs). We present the monolithic fabrication of an active photopixel made in InSb on a GaAs substrate that is suitable for large-scale integration into an FPA. Pixel addressing is provided by the cointegration of a GaAs MESFET with an InSb photodiode (PD). Pixel fabrication was achieved by developing novel materials and process steps, including isolation etches, a gate recess etch, and low temperature processes, to make Ohmic contacts to both the GaAs and InSb devices. Detailed electrical and optical measurements in an FTIR demonstrated that the PD was sensitive to radiation in the range of 3– 5~\mu \textm at room temperature, and that the device could be isolated from its contacts using the integrated MESFET. This heterogeneous technology creates great potential to realize a new type of monolithic FPA of addressable pixels for imaging in the MWIR range. [ABSTRACT FROM AUTHOR] more...

GaAs nanowire (NW)-based metal–semiconductor field-effect transistors (MESFETs) were constructed on flexible plastic substrates by a conventional top–down approach. The top–down approach utilized in this paper combines photolithography of high-quality GaAs bulk wafers with anisotropic chemical etching processes for preparation of GaAs NWs and photolithographic processes for formation of metal electrodes. For a representative GaAs NW-based MESFET, peak transconductance, the Ion/Ioff ratio, and the subthreshold slope are estimated to be approximately 19.7 \mu\S, \sim\!\!\10^7, and \sim100 mV/dec, respectively. The electrical characteristics of the GaAs NW-based MESFETs were maintained during 3000 times of bending cycles under maximal tensile strains of 0.77% and 1.02%. These results demonstrate the possibility of using these devices in high-speed and high-performance flexible electronics. [ABSTRACT FROM AUTHOR] more...

This paper describes a miniaturized monolithic-microwave integrated-circuit (MMIC) analog phase shifter using two quarter-wave-length transmission lines. A conventional analog phase shifter employs an analog phase-shifter topology using a 3-dB 90° branch-line hybrid requiring four quarter-wave-length transmission lines. Thus, in the first stage of our study, we present a new analog phase-shifter topology using only two quarter-wave-length transmission lines. The phase shifter here has only one-half as many transmission tines as a conventional analog phase shifter using a 3-dB 90° branch-line hybrid, and the circuit can be miniaturized to less than one-fourth as compared to the conventional analog phase shifter. Furthermore, we show that the operating frequency range of the phase shifter is very wide and can obtain large phase variation with small capacitance variation. Next, an experimental Ku-band MMIC analog phase shifter is presented. A phase shift of more than 180° and an insertion loss of 3.6±1.1 dB are obtained at the frequency range from 12 to 14 GHz. The chip size of the experimental MMIC phase shifter is less than 3.0 mm2 [ABSTRACT FROM PUBLISHER] more...

A phenomenologically based transient SPICE model was developed for GaAs MESFETs. The model accounts for both trapping and detrapping effects; hence, it can simultaneously simulate low-frequency dispersion and gate-lag characteristics. This is different from conventional models, which can simulate either effect, but not both. The present model has been used to describe both surface- and substrate-related trapping phenomena in epitaxial or ion-implanted MESFETs. The model was experimentally verified in terms of pulsed I-V characteristics and pulsed AC response [ABSTRACT FROM PUBLISHER] more...

This paper reports a study on the fabrication technology of high performance functional devices, where high temperature superconductor and compound semiconductor devices are monolithically integrated on the same substrate. We investigated optimal conditions for epitaxial liftoff process and succeeded in fabricating HTS device and GaAs MESFET on SrTiO/sub 3/ substrate without degrading characteristics of superconductor and semiconductor devices. We also carried out basic integrated circuit fabrication processes such as patterning and etching for quasi-monolithic structure. The results confirmed that fabricating high performance functional devices is feasible. [ABSTRACT FROM PUBLISHER] more...

A self-aligned unidirectional planar GaAs nanowire (NW) array is realized by growing on (110) GaAs substrates through the Au-catalyzed vapor–liquid–solid mechanism. All NWs on (110) substrates propagate along the [00-1] direction, yielding planar NWs with trapezoidal cross sections where the top surface and sidewalls are identified by micro X-ray diffraction analysis to be [110], [010], and [100] facets, respectively. Depletion-mode long-channel metal–semiconductor field-effect transistors using these [00-1] GaAs NWs as channels exhibit well-defined dc output and transfer characteristics, confirming the high material quality of the NWs. Completely ordered site controlled arrays of planar NWs are demonstrated by growing on (110) substrates with Au catalyst nanoparticles patterned using electron beam lithography. [ABSTRACT FROM AUTHOR] more...