Semiconductor Research Institute of Semiconductor Research Foundation

Sendai-shi, Japan

Semiconductor Research Institute of Semiconductor Research Foundation

Sendai-shi, Japan
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Yasuda A.,National Institute of Technology, Tsuruoka College | Kurabayashi T.,Akita University | Kurabayashi T.,Semiconductor Research Institute of Semiconductor Research Foundation | Suto K.,Semiconductor Research Institute of Semiconductor Research Foundation | Nishizawa J.-I.,Semiconductor Research Institute of Semiconductor Research Foundation
Journal of Nanoscience and Nanotechnology | Year: 2017

We fabricated p-n-junction-type and Schottky barrier (SB)-type lead telluride (PbTe) mid-infrared focal plane arrays (FPAs) using a flip-chip bonder. The detection wavelength peak of the SB-type FPA shifted from 6.10 μm to 4.95 μm as the ambient temperature was increased from -258.15 °C to -148.15 °C. At -196.5 °C, the detection wavelength peak and cut-off wavelength were 5.68 μm and 6.16 μm, respectively. The p-n-junction-type FPA yielded the sharpest photoconductivity spectrum among the investigated devices, presumably because of the Tl-related deep levels in its p-type PbTe epitaxial layer. These deep levels absorb the mid-infrared light and cut off the detection wavelength range. Thus, the p-n-junction-type FPAs are expected to be employed in vision cameras and sensors with selectable mid-infrared wavelengths. Meanwhile, the SB-type FPA has a high dielectric constant; consequently, it develops a wide depletion layer that detects a wide range of mid-infrared wavelengths. FPAs based on the PbTe system are potentially implementable in simple, highly sensitive, mid-infrared imaging devices with a wide scan range. Copyright © 2017 American Scientific Publishers All rights reserved.


Yasuda A.,National Institute of Technology, Tsuruoka College | Yasuda A.,Tohoku University | Takahashi Y.,Tohoku University | Suto K.,Semiconductor Research Institute of Semiconductor Research Foundation | Nishizawa J.-I.,Semiconductor Research Institute of Semiconductor Research Foundation
Journal of Crystal Growth | Year: 2017

We propose the use of heavily impurity-doped Pb1- xSnxTe/PbTe epitaxial layers grown via the temperature difference method under controlled vapor pressure (TDM-CVP) liquid-phase epitaxy (LPE) for the preparation of IV–VI compounds for mid- to far-infrared optical device applications. A flat surface morphology and the distribution of a constant Sn concentration for 0.05 ≤ x ≤ 0.33 were observed in the epitaxial layers using electron-probe microanalysis. The segregation coefficient of Sn in Pb1- xSnxTe grown via TDM-CVP LPE (Tg = 640 °C) was xS Sn/xL Sn = 0.28. The appearance of the Fermi level pinning and persistent photoconductivity effects in In-doped PbSnTe were also proposed; we estimated that the activation energies of these processes were 2.8 and 39.7 meV, respectively, based on the In-doped Pb1- xSnxTe carrier profile as a function of ambient temperature. In Hall mobility measurements, Sn was assumed to be a main scattering center in the Pb1- xSnxTe epitaxial crystals. The impurity effect was also observed in Pb1- xSnxTe epitaxial growth, similar to the effects observed for Tl-doped PbTe bulk crystals. We concluded that the heavily doped Pb1- xSnxTe crystals grown via TDM-CVP LPE can be used to fabricate high-performance mid- to far-infrared optical devices. © 2017 Elsevier B.V.


Yasuda A.,National Institute of Technology, Tsuruoka College | Yasuda A.,Tohoku University | Suto K.,Semiconductor Research Institute of Semiconductor Research Foundation | Nishizawa J.-I.,Semiconductor Research Institute of Semiconductor Research Foundation
Results in Physics | Year: 2016

Reverse-biased PbSnTe/PbTe double heterojunction diodes uniquely exhibit negative resistance. This property is assumed to originate from point defects in the deep levels of the diode crystal structure. © 2016 The Authors.


Yasuda A.,National Institute of Technology, Tsuruoka College | Yasuda A.,Tohoku University | Suto K.,Semiconductor Research Institute of Semiconductor Research Foundation | Takahashi Y.,Tohoku University | Nishizawa J.-I.,Semiconductor Research Institute of Semiconductor Research Foundation
Infrared Physics and Technology | Year: 2014

We fabricated a heavily Bi-doped (xBi ≈ 2 × 1019 cm-3) PbTe p-n homojunction diode that detects mid-infrared wavelengths by the temperature difference method (TDM) under controlled vapor pressure (CVP) liquid phase epitaxy (LPE). The photocurrent density produced by the heavily Bi-doped diode sample is approximately 20 times and 3 times greater than that produced by an undoped and heavily In-doped sample, respectively. By varying the ambient temperature from 15 K to 225 K, the detectable wavelength is tunable from 6.18 μm to 4.20 μm. The peak shift of the detectable wavelength is shorter in the heavily Bi-doped sample than in the undoped sample, consistent with our previously proposed model, in which Bi-Bi nearest donor-acceptor pairs are formed in the heavily Bi-doped PbTe liquid phase epitaxial layer. Current-voltage (I-V) measurements of the heavily Bi-doped diode sample under infrared exposure at 77 K indicated a likely leak in the dark current, arising from the deeper levels. From the dark I-V measurements, the activation energy of the deep level was estimated as 0.067 eV, close to the energy of the deep Tl-doped PbTe acceptor layer. We conclude that the deep level originates from the Tl-doped p-type epitaxial layer. © 2014 Elsevier B.V.


Yasuda A.,National Institute of Technology, Tsuruoka College | Yasuda A.,Tohoku University | Suto K.,Semiconductor Research Institute of Semiconductor Research Foundation | Nishizawa J.-I.,Semiconductor Research Institute of Semiconductor Research Foundation
Materials Science in Semiconductor Processing | Year: 2014

PbSnTe/PbTe double hetero-diode structures were grown by temperature difference method under controlled vapor pressure (TDM-CVP) liquid-phase epitaxy (LPE). These laser diode (LD) structures were of the PbTe (Bi)/Pb 1-xSnxTe/PbTe (undoped substrate) double hetero (DH) type. The peak shift of the wavelength emitted by the fabricated diodes was recorded and it was found that they successfully lased from 15 K to over 77 K (liquid nitrogen temperature) at a slightly lower threshold current density than standard LPEs fabricated via the slow-cooling method. In addition, the lasing peak wavelength was longer than spontaneous emissions. The laser spectra of diodes with varying Sn concentrations (x) in the active layer were observed, and their intensities were recorded as a function of the wavelength. Very sharp lasing spectra were obtained between 6.5 μm and 9.4 μm (x=0-0.11), clarifying that the stoichiometry control possible with TDM-CVP is suitable for fabricating optical devices. In addition, it was demonstrated that TDM-CVP is appropriate for fabricating infrared optical devices constructed from Pb xSn1-xTe systems. © 2014 Elsevier Ltd.


Yasuda A.,National Institute of Technology, Tsuruoka College | Sasaki T.,University of Shizuoka | Sasaki T.,Semiconductor Research Institute of Semiconductor Research Foundation | Suto K.,Semiconductor Research Institute of Semiconductor Research Foundation | Nishizawa J.-I.,Semiconductor Research Institute of Semiconductor Research Foundation
Infrared Physics and Technology | Year: 2015

Bi- or In-doped n-PbTe/p-PbSnTe/Tl-doped p-PbTe double-hetero (DH) diode structures were fabricated using the temperature difference method under controlled vapour pressure (TDM-CVP) liquid-phase epitaxy (LPE). We fabricated a PbSnTe/PbTe DH-junction laser diode (LD) using TDM-CVP LPE and subsequently obtained sharp lasing spectra between 7.2 (1390 cm-1) and 9.4 μm (1070 cm-1) by varying the ambient temperature of the diode. When the fabricated Pb0.89Sn0.11Te/PbTe LD was used to image Si wafers with different resistivities, we obtained a clear contrast between the wafers. We also obtained the mid-infrared imaging spectrum of benzoic acid (BA) using the fabricated Pb0.89Sn0.11Te/PbTe LD, and the absorbance image obtained using the fabricated LD showed good agreement with a Fourier transform infrared (FTIR) spectrum. We observed sharp lasing spectra between 7.20 (1390 cm-1) and 7.80 μm (1280 cm-1) by varying the ambient temperature of the diode sample. We observed some absorption peaks in the obtained infrared absorption spectra of para-nitrobenzoic acid (PNBA) and BA; a peak at approximately 7.45 μm (1345 cm-1) in the spectrum of PNBA originated from NO2 symmetric stretching bands. Moreover, we observed that the other peaks in these spectra also match peaks from conventional FTIR spectra. © 2015 Elsevier B.V. All rights reserved.

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