Center for Quantum Devices - Most Downloaded Journal Articles

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21.	Al_xGa_1-xN Materials and Device Technology for Solar Blind Ultraviolet Photodetector Applications R. McClintock, P. Sandvik, K. Mi, F. Shahedipour, A. Yasan, C. Jelen, P. Kung, and M. Razeghi SPIE Conference, San Jose, CA, Vol. 4288, pp. 219-- January 22, 2001 ...[Visit Journal] There has been a growing interest for the development of solar blind ultraviolet (UV) photodetectors for use in a variety of applications, including early missile threat warning, flame monitoring, UV radiation monitoring and chemical/biological reagent detection. The Al_xGa_1-xN material system has emerged as the most promising approach for such devices. However, the control of the material quality and the device technology are still rather immature. We report here the metalorganic chemical vapor deposition, the n-type and the p-type doping of high quality Al_xGa_1-xN thin films on sapphire substrates over a wide range of Al concentration. [reprint (PDF)]
21.	Continuous wave quantum cascade lasers with 5.6 W output power at room temperature and 41% wall-plug efficiency in cryogenic operation F. Wang, S. Slivken, D. H. Wu, Q. Y. Lu, and M. Razeghi AIP Advances 10, 055120-- May 19, 2020 ...[Visit Journal] In this paper, we report a post-polishing technique to achieve nearly complete surface planarization for the buried ridge regrowth processing of quantum cascade lasers. The planarized device geometry improves the thermal conduction and reliability and, most importantly, enhances the power and efficiency in continuous wave operation. With this technique, we demonstrate a high continuous wave wall-plug efficiency of an InP-based quantum cascade laser reaching ∼41% with an output power of ∼12 W from a single facet operating at liquid nitrogen temperature. At room temperature, the continuous wave output power exceeds the previous record, reaching ∼5.6 W. [reprint (PDF)]
21.	The new oxide paradigm for solid state ultraviolet photodetectors D. J. Rogers, P. Bove, X. Arrateig, V. E. Sandana, F. H. Teherani, M. Razeghi, R. McClintock, E. Frisch, S. Harel, Proceedings Volume 10533, Oxide-based Materials and Devices IX; 105331P-- March 22, 2018 ...[Visit Journal] The bandgap of wurzite ZnO layers grown on 2 inch diameter c-Al₂O₃ substrates by pulsed laser deposition was engineered from 3.7 to 4.8 eV by alloying with Mg. Above this Mg content the layers transformed from single phase hcp to mixed hcp/fcc phase before becoming single phase fcc above a bandgap of about 5.5 eV. Metal-Semiconductor-Metal (MSM) photodetectors based on gold Inter-Digitated-Transducer structures were fabricated from the single phase hcp layers by single step negative photolithography and then packaged in TO5 cans. The devices gave over 6 orders of magnitude of separation between dark and light signal with solar rejection ratios (I270 : I350) of over 3 x 10⁵ and dark signals of 300 pA (at a bias of −5V). Spectral responsivities were engineered to fit the “Deutscher Verein des Gas- und Wasserfaches” industry standard form and gave over two decade higher responsivities (14 A/W, peaked at 270 nm) than commercial SiC based devices. Homogeneous Ga₂O₃ layers were also grown on 2 inch diameter c-Al₂O₃ substrates by PLD. Optical transmission spectra were coherent with a bandgap that increased from 4.9 to 5.4 eV when film thickness was decreased from 825 to 145 nm. X-ray diffraction revealed that the films were of the β-Ga₂O₃ (monoclinic) polytype with strong (−201) orientation. β-Ga₂O₃ MSM photodetectors gave over 4 orders of magnitude of separation between dark and light signal (at −5V bias) with dark currents of 250 pA and spectral responsivities of up to 40 A/W (at -0.75V bias). It was found that the spectral responsivity peak position could be decreased from 250 to 230 nm by reducing film thickness from 825 to 145 nm. This shift in peak responsivity wavelength with film thickness (a) was coherent with the apparent bandgap shift that was observed in transmission spectroscopy for the same layers and (b) conveniently provides a coverage of the spectral region in which MgZnO layers show fcc/hcp phase mixing. [reprint (PDF)]
21.	Toward realization of small-size dual-band long-wavelength infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices Romain Chevallier, Abbas Haddadi, Manijeh Razeghi Solid-State Electronics 136, pp. 51-54-- June 20, 2017 ...[Visit Journal] In this study, we demonstrate 12 × 12 µm² high-performance, dual-band, long-wavelength infrared (LWIR) photodetectors based on InAs/GaSb/AlSb type-II superlattices. The structure consists of two back-to-back heterojunction photodiodes with 2 µm-thick p-doped absorption regions. High quality dry etching combined with SiO₂ passivation results in a surface resistivity value of 7.9 × 10⁵ Ω·cm for the longer (red) channel and little degradation of the electrical performance. The device reaches dark current density values of 4.5 × 10⁻⁴ A/cm² for the longer (red) and 1.3 × 10⁻⁴ A/cm² for the shorter (blue) LWIR channels at quantum efficiency saturation. It has 50% cut-off wavelengths of 8.3 and 11.2 µm for the blue and red channel, respectively, at 77 K in back-side illumination configuration and exhibits quantum efficiencies of 37% and 29%, respectively. This results in specific detectivity values of 2.5 × 10¹¹ cm·Hz^½/W and 1.3 × 10¹¹ cm·Hz^½/W at 77 K. [reprint (PDF)]
21.	Ga₂O₃ Metal-oxide-semiconductor Field Effect Transistors on Sapphire Substrate by MOCVD Ji-Hyeon Park, Ryan McClintock and Manijeh Razeghi Semiconductor Science and Technology, Volume 34, Number 8-- June 26, 2019 ...[Visit Journal] Si-doped gallium oxide (Ga₂O₃) thin films were grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD) and fabricated into metal oxide semiconductor field effect transistors (MOSFETs). The Ga₂O₃ MOSFETs exhibited effective gate modulation of the drain current with a complete channel pinch-off for VG < −25 V, and the three-terminal off-state breakdown voltage was 390 V. The device shows a very low gate leakage current (~50 pA/mm), which led to a high on/off ratio of ~10⁸. These transistor characteristics were stable from room temperature to 250 °C [reprint (PDF)]
21.	Advances in antimonide-based Type-II superlattices for infrared detection and imaging at center for quantum devices M. Razeghi, A. Haddadi, A.M. Hoang, E.K. Huang, G. Chen, S. Bogdanov, S.R. Darvish, F. Callewaert, R. McClintock Infrared Physics & Technology, Volume 59, Pages 41-52 (2013)-- July 1, 2013 ...[Visit Journal] Type-II InAs/GaSb superlattices (T2SLs), a system of multi-interacting quantum wells, was introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this material system has drawn a lot of attention especially for infrared detection. In recent years, T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process which elevated the performances of T2SL-based photo-detectors to a comparable level to the state-of-the-art material systems for infrared detection such as Mercury Cadmium Telluride (MCT). In this paper, we will present the current status of T2SL-based photo-detectors and focal plane arrays for imaging in different infrared regions, from SWIR to VLWIR, and the future outlook of this material system. [reprint (PDF)]
21.	High-speed short wavelength infrared heterojunction phototransistors based on type II superlattices Jiakai Li; Arash Dehzangi; Donghai Wu; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128813-- January 31, 2020 ...[Visit Journal] A two terminal short wavelength infrared heterojunction phototransistors based on type-II InAs/AlSb/GaSb on GaSb substrate are designed fabricated and presented. With the base thickness of 40 nm, the device exhibited 100% cut-off wavelengths of ~2.3 μm at 300K. The saturated peak responsivity value is of 325.5 A/W at 300K, under front-side illumination without any anti-reflection coating. A saturated optical gain at 300K was 215 a saturated dark current shot noise limited specific detectivity of 4.9×10¹¹ cm·Hz^½/W at 300 K was measured. Similar heterojunction phototransistor structure was grown and fabricated with different method of processing for high speed testing. For 80 μm diameter circular diode size under 20 V applied reverse bias, a −3 dB cut-off frequency of 1.0 GHz was achieved, which showed the potential of type-II superlattice based heterojunction phototransistors to be used for high speed detection. [reprint (PDF)]
21.	Material and design engineering of (Al)GaN for high-performance avalanche photodiodes and intersubband applications M. Razeghi and C. Bayram SPIE Proceedings, Dresden, Germany (May 4-6, 2009), Vol. 7366, p. 73661F-1-- May 20, 2009 ...[Visit Journal] Numerous applications in scientific, medical, and military areas demand robust, compact, sensitive, and fast ultraviolet (UV) detection. Our (Al)GaN photodiodes pose high avalanche gain and single-photon detection efficiency that can measure up to these requirements. Inherit advantage of back-illumination in our devices offers an easier integration and layout packaging via flip-chip hybridization for UV focal plane arrays that may find uses from space applications to hostile-agent detection. Thanks to the recent (Al)GaN material optimization, III-Nitrides, known to have fast carrier dynamics and short relaxation times, are employed in (Al)GaN based superlattices that absorb in near-infrared regime. In this work, we explain the origins of our high performance UV APDs, and employ our (Al)GaN material knowledge for intersubband applications. We also discuss the extension of this material engineering into the far infrared, and even the terahertz (THz) region. [reprint (PDF)]
21.	High-Performance Focal Plane Arrays Based on InAs-GaSb Superlattices with a 10-micron Cutoff Wavelegth P.Y. Delaunay, B.M. Nguyen, D. Hoffman and M. Razeghi IEEE Journal of Quantum Electronics, Vol. 44, No. 5, p. 462-467-- May 1, 2008 ...[Visit Journal] We report on the demonstration of a focal plane array based on Type-II InAs/GaSb superlattices grown on N-type GaSb substrate with a 50%-cutoff wavelength at 10 μm. The surface leakage occurring after flip-chip bonding and underfill in the Type-II devices was suppressed using a double heterostructure design. The R₀A of diodes passivated with SiO₂ was 23 Ω·cm² after underfill. A focal plane array hybridized to an Indigo readout integrated circuit demonstrated a noise equivalent temperature difference of 33 mK at 81 K, with an integration time of 0.23 ms. [reprint (PDF)]
21.	High Power Mid-Infrared Quantum Cascade Lasers Grown on Si Steven Slivken, Nirajman Shrestha, and Manijeh Razeghi Photonics, vol. 9, 626 ...[Visit Journal] This article details the demonstration of a strain-balanced, InP-based mid-infrared quantum cascade laser structure that is grown directly on a Si substrate. This is facilitated by the creation of a metamorphic buffer layer that is used to convert from the lattice constant of Si (0.543 nm) to that of InP (0.587 nm). The laser geometry utilizes two top contacts in order to be compatible with future large-scale integration. Unlike previous reports, this device is capable of room temperature operation with up to 1.6 W of peak power. The emission wavelength at 293 K is 4.82 um, and the device operates in the fundamental transverse mode. [reprint (PDF)]
21.	On the performance and surface passivation of type-II InAs/GaSb superlattice photodiodes for the very-long- wavelength infrared A. Hood, M. Razeghi, E. Aifer, G.J. Brown Applied Physics Letters 87 (1)-- October 10, 2005 ...[Visit Journal] We demonstrate very-long-wavelength infrared Type-II InAs/GaSb superlattice photodiodes with a cutoff wavelength (λ_c,50%) of 17 μm. We observed a zero-bias, peak Johnson noise-limited detectivity of 7.63×10⁹ cm·Hz^½/W at 77 K with a 90%-10% cutoff width of 17 meV, and quantum efficiency of 30%. Variable area diode zero-bias resistance-area product (R₀A) measurements indicated that silicon dioxide passivation increased surface resistivity by nearly a factor of 5, over unpassivated photodiodes, and increased overall R₀A uniformity. The bulk R₀A at 77 K was found to be 0.08 Ω·cm², with RA increasing more than twofold at 25 mV reverse bias. [reprint (PDF)]
21.	Quantum Dot Infrared Photodetectors: Comparison Experiment and Theory H. Lim, W. Zhang, S. Tsao, T. Sills, J. Szafraniec, K. Mi, B. Movaghar, and M. Razeghi Physical Review B, 72-- August 17, 2005 ...[Visit Journal] We present data and calculations and examine the factors that determine the detectivities in self-assembled InAs and InGaAs based quantum dot infrared photodetectors (QDIPs). We investigate a class of devices that combine good wavelength selectivity with “high detectivity.” We study the factors that limit the temperature performance of quantum dot detectors. For this we develop a formalism to evaluate the optical absorption and the electron transport properties. We examine the performance limiting factors and compare theory with experimental data. We find that the notion of a phonon bottleneck does not apply to large-diameter lenslike quantum dots, which have many closely spaced energy levels. The observed strong decrease of responsivity with temperature is ultimately due to a rapid thermal cascade back into the ground states. High temperature performance is improved by engineering the excited state to be near the continuum. The good low temperature (77 K) performance in strongly bound QDIPs is shown to be due to the high gain and the low noise achievable in these micron size devices. [reprint (PDF)]
21.	InTlSb alloys for infrared detection E. Bigan, Y.H. Choi, G. Labeyrie, and M. Razeghi Proceedings, SPIE Nonlinear Optics for High-Speed Electronics and Optical Frequency Conversion, Vol. 2145-- January 24, 1994 ...[Visit Journal] InTISb alloys have been grown by low-pressure metalorganic chemical vapor deposition, and characterized. Photoconductors exhibit a cutoff wavelength that can be tailored from 5.5 μm up to 9 μm by varying the thallium content. Experimental observations suggest that this can be further extended by increasing the thallium content. An InTISb photoconductor having a 9 μm cutoff wavelength exhibited a D* of 10⁹ cm·Hz^½·W^-1 at 7 μm operating wavelength. [reprint (PDF)]
21.	Ammonium Sulfide Passivation of Type-II InAs/GaSb Superlattice Photodiodes A. Gin, Y. Wei, A. Hood, A. Bajowala, V. Yazdanpanah, M. Razeghi and M.Z. Tidrow Applied Physics Letters, 84 (12)-- March 22, 2004 ...[Visit Journal] We report on the surface passivation of Type-II InAs/GaSb superlattice photodetectors using various ammonium sulfide solutions. Compared to unpassivated detectors, zero-bias resistance of treated 400 µm×400 µm devices with 8 µm cutoff wavelength was improved by over an order of magnitude to ~20 kΩ at 80 K. Reverse-bias dark current density was reduced by approximately two orders of magnitude to less than 10 mA/cm² at –2 V. Dark current modeling, which takes into account trap-assisted tunneling, indicates greater than 70 times reduction in bulk trap density for passivated detectors. [reprint (PDF)]
21.	Breakthroughs Bring THz Spectroscopy, Sensing Closer to Mainstream Manijeh Razeghi, Quanyong Lu, Santanu Manna, Donghai Wu & Steven Slivken Photonics Spectra, December Issue, pp. 48-- December 1, 2016 ...[Visit Journal] The terahertz (THz) electromagnetic spectrum (1 to 10 THz), sitting between the infrared wavelengths on the higher frequency side and microwaves on the lower frequency side, lies unique and important properties. THz waves can pass through a number of materials, including synthetics, textiles, paper and cardboard. Many biomolecules, proteins, explosives or narcotics feature characteristic absorption I ines - so-called spectral "fingerprints" - at frequencies between 1 and 10 THz. [reprint (PDF)]
21.	Electron Transport Properties of Ga[0.51]In[0.49]P for Device Applications C. Besikci and M. Razeghi IEEE Transactions on Electron Devices 41 (6)-- June 1, 1994 ...[Visit Journal] We present Monte Carlo calculations of steady-state and transient electron transport properties of Ga0.51In0.49P. We have made a simulation-based comparison between Ga0.51In0.49P and AlxGa1-xAs (x = 0.2, 0.3). Our Monte Carlo data show that transport properties of Ga0.51In0.49P are favorable, and when the other advantages of the GaInP/GaAs system are also taken into account. this material is a good choice to replace AlxGa1-xAs (x greater-than-or-equal-to 0.3). We have also calculated electron drift and Hall mobilities in Ga0.51In0.49P as a function of impurity concentration and temperature, and determined the effects of different scattering mechanisms on the low-field mobility. Calculated results are in good agreement with the measurements on metal organic chemical vapor deposition (MOCVD) grown samples with Hall mobilities within a factor of 0.5 of the calculated theoretical limit. It has also been found that alloy scattering is an important mobility degrading mechanism in lightly doped material at low temperatures. [reprint (PDF)]
21.	Future of Al_xGa_1-xN Materials and Device Technology for Ultraviolet Photodetectors P. Kung, A. Yasan, R. McClintock, S. Darvish, K. Mi, and M. Razeghi SPIE Conference, San Jose, CA, Vol. 4650, pp. 199-- May 1, 2002 ...[Visit Journal] Design of the photodetector structure is one of the key issues in obtaining high performance devices; especially the thickness of the intrinsic region for p-i-n photodiodes is a crucial value and needs to be optimized. We compare the performance of the p-i-n photodiodes with different widths for the depletion region, which shows a trade-off between speed and responsivity of the devices. [reprint (PDF)]
21.	Performance enhancement of GaN ultraviolet avalanche photodiodes with p-type delta-doping C. Bayram, J.L. Pau, R. McClintock and M. Razeghi Applied Physics Letters, Vol. 92, No. 24, p. 241103-1-- June 16, 2008 ...[Visit Journal] High quality delta-doped p-GaN is used as a means of improving the performance of back-illuminated GaN avalanche photodiodes (APDs). Devices with delta-doped p-GaN show consistently lower leakage current and lower breakdown voltage than those with bulk p-GaN. APDs with delta-doped p-GaN also achieve a maximum multiplication gain of 5.1×10⁴, more than 50 times higher than that obtained in devices with bulk p-GaN. The better device performance of APDs with delta-doped p-GaN is attributed to the higher structural quality of the p-GaN layer achieved via delta-doping. [reprint (PDF)]
21.	High power InAsSb/InPAsSb/InAs mid-infrared lasers A. Rybaltowski, Y. Xiao, D. Wu, B. Lane, H. Yi, H. Feng, J. Diaz, and M. Razeghi Applied Physics Letters 71 (17)-- October 27, 1997 ...[Visit Journal] We demonstrate high-power InAsSb/InPAsSb laser bars (λ ≈ 3.2 μm) consisting of three 100 μm-wide laser stripes of 700 μm cavity length, with peak output power up to 3 W at 90 K, and far-fields for the direction perpendicular to the junction as narrow as 12° full width half maximum. Spectra and far-field patterns of the laser bars are shown to have excellent characteristics for a wide range of operating conditions, suggesting the possibility of even higher light power emission with good beam quality. Joule heating is shown to be the major factor limiting higher power operation. [reprint (PDF)]
21.	Al_xGa_1-xN p-i-n Photodiodes on Sapphire Substrates D. Walker, P. Kung, P. Sandvik, J. Wu, M. Hamilton, I.H. Lee, J. Diaz, and M. Razeghi SPIE Conference, San Jose, CA, -- January 27, 1999 ...[Visit Journal] We report the fabrication and characterization of Al_xGa1-xN p-i-n photodiodes (0.05 ≤ to X ≤ 0.30) grown on sapphire by low-pressure metalorganic chemical vapor deposition. The devices present a visible-rejection of about four orders of magnitude with a cutoff wavelength that shifts from 350 nm to 291 nm. They also exhibit a constant responsivity for five decades (30 mW/m² to 1 kW/m²) of optical power density. Using capacitance measurements, the values for the acceptor concentration in the p-Al_xGa_1-xN region and the unintentional donor concentration in the intrinsic region are found. Photocurrent decays are exponential for high load resistances, with a time constant that corresponds to the RC product of the system. For low load resistances the transient response becomes non-exponential, with a decay time longer than the RC constant. [reprint (PDF)]
21.	AlGaN ultraviolet photoconductors grown on sapphire D. Walker, X. Zhang, P. Kung, A. Saxler, S. Javadpour, J. Xu, and M. Razeghi Applied Physics Letters 68 (15)-- April 8, 1996 ...[Visit Journal] Al_xGa_1−xN (0≤x≤0.50) ultraviolet photoconductors with a minimum cutoff wavelength shorter than 260 nm have been fabricated and characterized. The AlGaN active layers were grown on (00⋅1) sapphire substrates by metalorganic chemical vapor deposition (MOCVD). The spectral responsivity of the GaN detector at 360 nm is about 1 A/W biased at 8 V at room temperature. The carrier lifetime derived from the voltage‐dependent responsivity is 0.13–0.36 ms. [reprint (PDF)]
21.	Self-Detecting Mid-Infrared Dual-Comb Spectroscopy Based on High-Speed Injection-Locked Quantum Cascade Lasers Yu Ma, Dapeng Wu, Ruixin Huang, Shichen Zhang, Binru Zhou, Zejun Ma, Yongqiang Sun, Junqi Liu, Ning Zhuo, Jinchuan Zhang, Shenqiang Zhai, Shuman Liu, Fengqi Liu, Manijeh Razeghi, and Quanyong Lu Adv. Photonics Res. 2500062 (2025) ...[Visit Journal] Dual-comb spectrometer based on quantum cascade lasers (QCLs) is gaining fast development and revolutionizing the precision measurement with high-frequency and temporal resolutions. In these measurements, high-bandwidth photodetectors are normally used for signal acquisition and processing, which complicates the measurement system. QCL is well-known for its picosecond gain-recovery time with an intrinsic bandwidth of tens of GHz. In this work, a compact self-detecting dual-comb spectroscopy (DCS) is demonstrated based on dispersion-engineered, high-speed packaged QCLs under coherent injection locking. The laser source is designed and fabricated into a hybrid-monolithic-integrated waveguide and epi-down packaged on a wideband-designed submount to fully explore the high-speed feature up to fourth-order harmonic state with a cutoff frequency of 40 GHz. The effective radio frequency (RF) injection locking diminishes the issue of optical feedback and enables high-bandwidth self-detection based on QCLs. Clear and stable multiheterodyne signal corresponding to a spectral range of 68 cm−1 and narrow comb tooth linewidth of ≈10 kHz is observed without using external detector or numerical process. The demonstrated broadband, high-power, self-detecting mid-infrared QCL DCS has a great potential for future applications of molecular sensing and spectroscopy. [reprint (PDF)]
21.	Influence of Residual Impurity Background on the Non-radiative Recombination Processes in High Purity InAs/GaSb superlattice Photodiodes E.C.F. da Silva, D. Hoffman, A. Hood, B. Nguyen, P.Y. Delaunay and M. Razeghi Applied Physics Letters, 89 (24)-- December 11, 2006 ...[Visit Journal] The influence of the impurity background on the recombination processes in type-II InAs/GaSb superlattice photodiodes with a cutoff wavelength of approximately 4.8 μm was investigated by electroluminescence measurements. Using an iterative fitting procedure based on the dependence of the quantum efficiency of the electroluminescence on the injection current, the Auger and Shockley-Read-Hall lifetimes were determined [reprint (PDF)]
21.	Quntum Cascade Laser Breakthrough for Advanced Remote Detection Manijeh Razeghi, Wenjia Zhou, Donghai Wu, Ryan McClintock, and Steven Slivken Photonics Spectra, November issue-- November 1, 2016 ...[Visit Journal] The atoms in a molecule can bend, stretch and rotate with respect to one another, and these excitations are largely optically active. Most molecules, from simple to moderately complex, have a characteristic absorption spectrum in the 3- to 14-µrn wavelength range that can be uniquely identified and quantified in real time. Infrared spectroscopy has been used to study these absorption features and develop different molecular "fingerprints." [reprint (PDF)]
21.	Monolithic Integration of GaInAs/InP Quantum Well Infrared Photodetectors on Si Substrate M. Erdtmann and M. Razeghi SPIE Conference, San Jose, CA, -- January 22, 2001 ...[Visit Journal] Using low-pressure metalorganic chemical vapor deposition, we have grown GaInAs/InP QWIP structures on GaAs-coated Si substrate. First, the procedure to optimize the epitaxy of the InP buffer layer on Si substrate is given. Excellent crystallinity and a mirror-like surface morphology were obtained by using both a two-step growth process at the beginning of the InP buffer layer growth and several series of thermal cycle annealing throughout the InP buffer layer growth. Second, results of fabricated GaInAs/InP QWIPs on Si substrate are presented. At a temperature of 80 K, the peak response wavelength occurs at 7.4 μm. The responsivities of QWIPs on both Si and InP substrates with identical structures are equal up to biases of 1.5 V. At a bias of 3 V, the responsivity of the QWIPs on Si substrate is 1.0 A/W. [reprint (PDF)]

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