Masayuki Mori

University of Toyama | U Toyama · Graduate School of Science and Engineering for Research

We achieved detailed characterization of resonant tunneling chaos generator circuits in microwave frequency range. The circuit is analogous to Duffing oscillator, where the third-order nonlinear potential term is emulated by the nonlinear current-voltage curve of the resonant tunneling diode. The circuit includes a periodic reset mechanism to outpu...

A hard-type oscillator is defined as an oscillator having stable fixed points within a stable limit cycle. For resonant tunneling diode (RTD) oscillators, using hard-type configuration has a significant advantage that it can suppress spurious oscillations in a bias line. We have fabricated hard-type oscillators using an InGaAs-based RTD, and demons...

Frequency delta-sigma modulator (FDSM) employing a variable frequency oscillator is a novel replacement of the classical delta-sigma modulators. This is advantageous for application to sensors, because an ADC can be intrinsically integrated with the sensors. We have already proposed to use this technique to various sensors. However, the signal-to-n...

Frequency delta sigma modulation (FDSM) is a unique analog to digital conversion technique featuring large dynamic range with wide frequency band width. It can be used for high performance digital-output sensors, if the oscillator in the FDSM is replaced by a variable frequency oscillator whose frequency depends on a certain external physical quant...

Purpose This paper aims to propose and demonstrate novel microphone sensors based on the frequency delta-sigma modulation (FDSM) technique, which replaces the conventional delta-sigma modulator in the delta-sigma analog-to digital converters. A key of the FDSM technology is to use a voltage-controlled oscillator (VCO) for converting an input analog...

Hard-type oscillators for ultrahigh frequency applications were proposed based on resonant tunneling diodes (RTDs) and a HEMT trigger circuit. The hard-type oscillators initiate oscillation only after external excitation. This is advantageous for suppressing the spurious oscillation in the bias line, which is one of the most significant problems in...

A resonant tunneling diode oscillator having a wide frequency variation range based on a novel MEMS resonator was proposed, which exploits the change in the signal propagation velocity on a coplanar waveguide according to a movable ground plane. First, we discussed the velocity modulation mechanism, and clarified the importance of the dielectric co...

The single crystalline InSb and GaSb thin films on the same Si(111) substrate is an essence of CMOS device fabrication. In this study, the growth of InSb has been observed on InGaSb intermediate layer grown on High Quality (HQ) GaSb buffer layer of single crystalline nature. In this case, InxGa1–xSb was initially grown on HQ GaSb/Si(111)-√3 × √3-Ga...

An investigation was performed on the heteroepitaxial growth of InxGa1–xSb on GaSb/Si(111)–√3 × √3-Ga substrate following a two-step growth method. The buffer layer flux ratio of Ga and Sb has been controlled precisely to grow a high-quality GaSb layer without twins, whereas the ratio of In and Ga varied for epitaxial InxGa1–xSb layers. The growth...

A strain sensor was fabricated based on a resonant tunneling diode (RTD) oscillator. This sensor uses strain-dependent frequency change of the RTD oscillator, and the frequency delta-sigma modulation technique, which can convert a frequency to a digital signal with wide dynamic range and wide bandwidth. The sensor consists of an oscillator using an...

The frequency delta-sigma modulation (FDSM) technique was applied to the microphone sensors. The FDSM is a superior analogue-to-digital conversion technique, which outputs wide band, large dynamic range digital signals without precision analogue components. In this implementation, a microwave cavity resonator having movable membrane on its one end,...

We investigated the heteroepitaxial growth of InSb on Ge(111) substrate via buffer layer grown under In-rich or Sb-rich condition. We found that high-quality InSb films can be grown on Ge(111) substrate by two-step growth procedure, in which the 10nm-thick buffer layer is grown by using In rich growth condition at lower temperature (LT) and then th...

Super regenerative detectors using a resonant tunneling diode (RTD) were fabricated and investigated for ultra-high frequency detectors. A key point is to use the RTD super regenerative detector for detecting much higher frequencies than the free-running oscillation frequency of the detector. This is possible owing to the superior high frequency ch...

This paper discusses the characteristics of the InSb/Si heterojunctions. Thin epitaxial layers of the InSb were grown on p-Si substrate by using the surface reconstruction controlled epitaxy. This epitaxial growth technique permits us to grow high quality InSb on Si (111) surface. The n-InSb/p-Si heterojunction pn diodes were fabricated with these...

This paper discusses characteristics of the InSb films on Ge substrate. To grow high quality InSb films on Ge substrate, we tried to optimize the growth conditions. We carried out the direct growth of the InSb films on Ge(111) substrate by using two-step growth procedure. At first, we studied the effect of the growth temperature and thickness of th...

Fluidic self-assembly (FSA) using molten metal bumps is one of the most promising heterogeneous integration (HI) technologies, which enable us to integrate devices made of various materials on various substrates. We can fabricate the metal bumps using Ga having diameters of 24, 18, 12, and 8 mu m with good yield. Using Ga has significant advantages...

A super regenerative detector employing a resonant tunneling diode (RTD) was investigated for THz wave detection. A key is to use extremely high order harmonics of the fundamental oscillation of the regenerative oscillator. This has various advantages, such as circuit simplicity, easy design, and low power consumption. The basic operation and the p...

CdTe/CdSe heterojunction solar cell structure is fabricated using a simple, easy and low-cost electrodeposition method. To fabricate this solar cell structure, CdSe and CdTe thin films are deposited onto FTO-coated glass substrates by low-cost electrodeposition method. The optimized growth conditions are first chosen for both CdSe and CdTe layers b...

This paper describes the fabrication process of the MEMS microphones on InP substrates. The process is based on ozone ashing of the photoresist to fabricate a hollow structure. This process was demonstrated to be damage-free, and suitable for integration with HEMTs.

This paper discusses ohmic contact formation of Sn-based alloys on n-InSb. Most critical problem, we encountered when using a Sn/Au/Ni/Ti/Au metal stack, is an anomalous alloy extension of the ohmic metal. This was found to be resulted from rapid diffusion of Au. It is demonstrated that by removing the Au under the Ti barrier layer good contact res...

RTD pulse generators were designed and fabricated for improved power performance. 10-ps class pulse width with higher peak power was demonstrated for the circuit having an exponentially tapered transmission line impedance converter.

Al2O3/InSb/Si quantum well MOSFETs were fabricated with a thin InSb channel layer grown directly on Si(111) substrates. The InSb thickness ranged from 6 to 25 nm. These thicknesses are close to the critical thickness of InSb on Si, when the InSb layer is grown using a special technique called surface reconstruction controlled epitaxy, which reduces...

A novel type of millimeter/submillimeter wave sampler based on resonant tunneling diodes (RTDs) was proposed, and its operation was confirmed by circuit simulation. It consists of an RTD pulse generator and an RTD detector. Owing to the fuse-like nonlinear I-V curve, highly sensitive sampling can be obtained. We also found that the effects of nonid...

The oscillators based on an active transmission line periodically loaded with RTD pairs are studied using circuit simulation with special attention to the behavior of harmonics. Generation of strong high order harmonic (9th) was observed. This is caused by the frequency locking in the high frequency passband. The harmonic oscillators based on this...

InSb is one of the most promising candidates for the channel layers of the post scaling LSIs, because it features highest electron mobility of 78,000 cm 2/(Vs) and highest saturation velocity of 5×10 7 cm/s among III-V compound semiconductors. High performance HEMTs based on InSb/InAlSb material system have been already demonstrated [1]. However, g...

This paper discusses the capacitance–voltage (C–V) characteristics of Al2O3/InSb/Si (1 1 1) MOS diodes grown using MBE via InSb bi-layer with special care to the surface reconstruction. This growth technique is based on our finding that the InSb layer grown on a Si (1 1 1) substrate is rotated by 30° with respect to the substrate under certain init...

We investigated the effects of initial In coverage for the preparation of InSb bilayer on electrical properties of InSb films grown by surface reconstruction controlled epitaxy. The electron mobility of the InSb films was affected by the initial In coverage of the In-induced surface reconstruction on Si(111) surface. Electron mobility increased wit...

We investigated the effects of initial In coverage for the preparation of InSb bilayer on electrical properties of InSb films grown by surface reconstruction controlled epitaxy. The electron mobility of the InSb films was affected by the initial In coverage of the In-induced surface reconstruction on Si(111) surface. Electron mobility increased wit...

The n-type InSb films were prepared on Si(111) substrates with a two-step growth method via an InSb bilayer. This growth method consists of an initial low-temperature InSb layer growth and a subsequent high-temperature InSb layer growth. In order to obtain a heteroepitaxial InSb film with a high electron mobility, the growth conditions of the first...

The n-type InSb films were prepared on Si(111) substrates with a two-step growth method via an InSb bilayer. This growth method consists of an initial low-temperature InSb layer growth and a subsequent high-temperature InSb layer growth. In order to obtain a heteroepitaxial InSb film with a high electron mobility, the growth conditions of the first...

We investigated the in-depth profile of electrical properties of InSb films grown on Si(111) substrates using various InSb bilayers. The InSb bilayers were prepared using three types of initial In-induced surface reconstructions on Si(111) substrates such as \sqrt{3}×\sqrt{3}-In, 2×2-In, and \sqrt{7}×\sqrt{3}-In. The InSb films were grown using a t...

We investigated the in-depth profile of electrical properties of InSb films grown on Si(111) substrates using various InSb bilayers. The InSb bilayers were prepared using three types of initial In-induced surface reconstructions on Si(111) substrates such as √3×√3-In, 2×2-In, and √7×√3-In. The InSb films were grown using a two-step growth procedure...

A third order harmonic oscillator has been proposed based on the resonant tunneling diode pair oscillators. This oscillator has significant advantages, good stability of the oscillation frequency against the load impedance change together with capability to output higher frequencies. Proper circuit operation has been demonstrated using circuit simu...

This paper proposes a traveling wave amplifier based on composite right/left handed (CRLH) transmission lines (TLs) periodically loaded with resonant tunneling diode (RTD) pairs. This TL can be regarded as a “lossy” TL with a negative loss because of the negative differential resistance of the RTD. This means that the TL can amplify signals while t...

V-shaped grooves were prepared by patterning of line and space (LS) using photolithography and Reactive Ion Etching (RIE), and anisotropic etching using hot KOH solution on the patterned 100 nm- SiO2/Si(001) substrate. The V-shaped grooves consist of two 〈111〉 planes. The width of grooves was varied from 1 to 10 μm while keeping intervals (line-sha...

The InSb films was grown on the patterned Si(001) substrate with line and space along with [110] direction without V-shaped grooves. In spite of the large lattice mismatch of about 19.3% between InSb and Si, the InSb film was heteroepitaxially grown on the line-shaped 〈001〉〈001〉 surfaces. The InSb(004) peak in the XRD (χ=0oχ=0o) patterns of the fil...

Active transmission lines loaded with resonant tunneling diode (RTD) pairs were investigated as possible THz amplifiers. The RTD pair consists of two RTDs connected serially and is biased by voltages of the same absolute value with opposite signs. The RTD pair has unique current-voltage characteristics at the intermediate node; the true negative re...

Two-step growth of an AlInSb film mediated by an InSb bi-layer on a Si(111) substrate was performed in a molecular beam epitaxy (MBE) chamber. The growth was observed by in situ reflection high energy electron diffraction. After the deposition, the samples were characterized by X-ray diffraction (XRD). It is confirmed that the grown AlInSb films we...

V-shaped grooves were prepared by patterning of line and space (LS) using photolithography and BHF etching, and anisotropic etching using hot KOH solution on patterned 100 nm-SiO2/Si(001) substrate. The V-shaped grooves consist of two <111> planes. The width of grooves was varied from 2 to 10 μm while keeping intervals (<001> planes with 1 μm width...

The heteroepitaxial growth of InSb films via InSb bi-layer (Si(111)-2 × 2-InSb surface reconstruction) was studied. The InSb bi-layer was able to be prepared by 1 monolayer Sb adsorption onto Si(111)-√7 × √3-In surface reconstruction, as well as the results with 2 × 2-In or √3 × √3-In. The InSb film grown via the √7 × √3-ln surface reconstruction w...

To achieve the high-temperature growth of heteroepitaxial InSb films on the InSb bi-layer, we studied the influence of substrate temperature of first layer deposition (Ts1) on the two-step growth procedure. Although the growth at higher Ts1 of 240 and 280 °C is difficult to achieve using the usual procedure due to the desorption of In atoms from th...

Tin oxide (SnO2) nanowires with a tetragonal structure were synthesized by thermal evaporation of tin grains at 900 °C. The obtained nanowires were doped with palladium. The morphology, crystal structure, and H2 gas sensing properties of undoped and Pd-doped SnO2 nanowires were investigated. SnO2 nanowires were approximately 30–200 nm in diameter a...

A new method for InSb heteroepitaxial growth on a Si substrate was introduced in our previous work, in which an InSb film was formed via an InSb bi-layer. In the present work, to study the effects of In and Sb individual layers on the InSb film quality, InSb was deposited onto an InSb bi-layer, In mono-layer, and Sb mono-layer on a Si substrate. It...

The In-Sb bi-layer (Si(111)-2×2-InSb surface reconstruction) was able to be prepared by 1 monolayer Sb adsorption onto Si(111)-√7×√3-In surface reconstruction, as well as results with 2×2-In and √3×√3-In. By using the √7×√3-In surface reconstruction with higher In coverage, the area covered in the In-Sb bi-layer increased, and the area covered by 2...

The heteroepitaxial growth of InSb film via AlSb buffer layer on a Si(111) substrate was performed in an ultra high vacuum. The grown InSb films were characterized by X-ray diffraction and atomic force microscopy. XRD patterns (ϕ-scan) of the samples showed different epitaxial relationship between InSb/Si and InSb/AlSb/Si. It is found that surface...

Aluminum antimonide (AlSb) layers with various thickness ranged from about 8 to 250 nm were grown at 520 °C as the buffer layer for the heteroepitaxial growth of InSb films on Si(001) substrates. InSb films were grown at 400 °C on the AlSb/Si(001), and were characterized by X-ray diffraction (XRD), atomic force microscope, as a function of the thic...

The structural deformations in Si/SiGe system during thermal annealing were investigated by means of atomic force microscope (AFM) and high-resolution X-ray diffraction (HRXRD). The (004) rocking curve measurements showed that the obvious fringes of rocking curve obtained from pre-annealing sample were faded out gradually and disappeared completely...

Low-temperature growth of InSb films on Si(1 1 1) substrate was performed in an ultra-high vacuum chamber by coevaporation of elemental Indium and Antimony. The grown InSb films were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM). Despite large lattice mismatch of about 19.3% between them (1 1 1) preferentially ori...

The heteroepitaxial growth of InSb films via In-induced surface reconstructions such as 2×2-In and √3×√3-In on a Si(111) substrate was carried out by using a two-step growth procedure in an ultra-high vacuum (UHV) chamber. The samples were characterized by high-energy electron diffraction (RHEED), X-ray diffraction (XRD), scanning tunneling microsc...

We propose a method for the growth of strain relaxed and smooth Si0.75Ge0.25 alloy layers on a Si(001) substrate. In this method, we have used an ultrathin amorphous Si (UTA-Si) layer as a buffer layer and implemented a two-step process to grow the top alloy layer. High-resolution x-ray diffraction studies show that the alloy layers are highly rela...

The interdiffusion at Si/SiGe interface with Ge mole fraction of 19.2%, and SiGe layer thickness of 283 nm was studied by high-resolution X-ray diffraction. The results showed that the obvious fringes of rocking curve obtained from pre-annealing sample faded out gradually and disappeared completely with increasing annealing temperature and prolongi...

It have been reported that in deposition onto the Si(111)-($7\times 7$) reconstruction under suitable conditions resulted in the formation of the ordered In nanocluster array structure. Such ordered array structures of metal nanoclusters are promising materials for an ultra-high density recording and nanocatalysis, etc. In the present report, we de...

The growth of InSb films on a Si(0 0 1) substrate with AlSb buffer layer was performed in an ultra high vacuum chamber (UHV) by a co-evaporation of elemental Indium (In) and antimony (Sb) sources. The samples were characterized by Auger electron spectroscopy (AES), X-ray diffraction (XRD) and atomic force microscopy (AFM). The surface morphology an...

Indium was deposited onto the Si(111)-7 × 7 reconstruction in order to form an ordered array structure of In nanoclusters. Using scanning tunneling microscopy, the annealing effects on the 0.12-monolayer (ML)-In nanoclusters and 0.24-ML-In nanoclusters have been investigated. In the case of 0.12-ML-In, four types of adsorption mechanism including t...

The application of self organized growth method (magic clustering method) for the formation of new type of nanocluster is reported. Sb has been deposited onto bare Si(1 1 1)–(7 × 7) reconstruction and onto In magic nanocluster array structure. And Sb interaction with substrate and atomic structural change have been studied using scanning tunneling...

The Si1-xGex(x ≈ 0.25) films were grown on Si(001) substrate using ultra-thin amorphous Si(UTA-Si) buffer layers with thickness from 0∼30 Å by molecular beam epitaxy. The films were mainly characterized by a reciprocal space mapping performed on a high-resolution X-ray diffraction. It is shown that the smooth and relaxed SiGe alloy layers are obtai...

The formation of a Sb/Si(001) interface with artificial surface structure is achieved by Sb adsorption onto the In(4 × 3) surface phase at RT followed by annealing between 230 and 280°C. RHEED and STM studies of the evolution of the surface morphology during annealing revealed that the new Sb-induced surface includes the reconstructed Si layer with...

AlSb is a more suitable material as buffer layers for the heteroepitaxial growth of InSb films on a Si(0 0 1) substrate than Ge. It reduces the large lattice mismatch of about 19.3% between Si and InSb to about 5.6%. The resistance of AlSb with stoichiometric composition is large enough for the measurement of electrical properties. InSb films grown...

The process of Sb adsorption onto Si(0 0 1)–In(4×3) surface phase has been studied using scanning tunneling microscopy (STM), reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES) techniques. Above 400 °C, Sb tends to destroy the initial In-induced phase and terminate the surface forming Sb/Si(0 0 1) interface. B...

During the study of Sb condensation on the Si(1 1 1)–In(√3×√3) surface phase we observed the formation of a new Sb-induced surface structure with (√7×√7) lattice below 450 °C. This phase may not be prepared by direct Sb deposition on the Si(1 1 1) surface. Instead, the substitution for In atoms from T4 bonding sites by incoming Sb and formation of...

We studied the formation of a twinned InSb molecular layer on Si(1 1 1) substrate (epitaxial relation InSb[1 1 2]∥Si[1 1 0]) by depositing 1-ML Sb on Si(1 1 1)–In(4×1) reconstruction at 210°C, using reflection high-energy electron diffraction, X-ray photoelectron spectroscopy and Auger electron spectroscopy. Sb adsorption replaces Si–In bonds in th...

Germanium is a suitable material as the buffer layer for the heteroepitaxial growth of InSb films on a Si(001) substrate. It reduces the large lattice mismatch of about 19.3% between Si and InSb to about 14.5%. InSb films grown on the islanded Ge buffer layers on a Si(001) substrate at elevated temperature are strongly oriented in 〈001〉 direction....

Direct growth of InSb on Si(111) substrate is achieved by suitably adjusting the growth rate and substrate temperature. In this report, we detail the role of stoichiometry and growth temperature in the evolution of reflection high-energy electron diffraction (RHEED) patterns, surface morphology and the crystal quality. InSb is grown on Si(111)-(7×7...

InSb films were grown on Si(001) substrates covered with Ge islands at 250-400°C by molecular beam epitaxy (MBE), and characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD) and optical microscope. The Ge islands were formed on Si(001) substrates by the Ge deposition of about 100 monolayers (ML) at 450°C. For t...

InSb films were grown on Si(001) substrates by molecular beam epitaxy using Ge buffer layers with thickness up to 1000 ML (monolayer). The surface morphology of Ge layers on which heteroepitaxy of InSb film is achieved, was observed using atomic force microscope (AFM). The density of Ge islands on Si(001) substrate rapidly increased with increase i...

InSb was grown on the Si(001), Ge(001) and GeSi(001) substrates by the coevaporation of elemental In and Sb sources. The grown films were characterized by AES (Auger electron spectroscopy), optical microscope, XRD (X-ray diffraction), SEM (scanning electron microscope) and ECP (electron channeling pattern), as a function of growth conditions, such...