Vertical Schottky Diodes Research Articles

Switching Performance up to 150°C of β-Ga2O3 Field-Plated Vertical Schottky Diodes for 0.3-1 a Forward Current and 300-900 V Reverse Voltage

In the past few decades, wide-bandgap SiC (3.3 eV) and GaN (3.4 eV) based semiconductor rectifiers have shown promising results in power electronic switching and control applications. [1] Recently, Ga2O3 has attracted significant interest for its outstanding potential in power electronics due to superior material properties and availability of high-quality substrate and n-type epistructures. [2,3] The energy band gap of Ga2O3 is in the range of 4.5 – 4.9 eV, which corresponds to a ~8 MV/cm theoretical breakdown electric field. Reverse breakdown voltages larger than 1 kV were reported for both unterminated Ga2O3 vertical rectifiers (1000 V and 1600 V) and field-plated Ga2O3 Schottky diode (1076 V and 2300 V) with an epi thickness of 8 µm and 20 µm, respectively. [4,5,6,7] Furthermore, the switching characteristics of Ga2O3 vertical Schottky diodes were also investigated, and the recovery time was in the range of 20 to 30 ns. [6,7] This indicates an impressive potential application for high power switching devices. In this study, field-plate edge-termination was utilized on a lightly doped 20 µm Ga2O3 epitaxial layer to greatly improve the Ga2O3 vertical rectifier breakdown voltage. In addition, we demonstrate that an 8 µm epitaxial layer of β-Ga2O3 on bulk conducting substrates can achieve forward currents in the 1 A range with a reverse breakdown voltage of 760 V. Field-plated edge-terminated (FPET) Schottky diodes with a reverse breakdown voltage of 2100 V (0.1 cm × 0.1 cm) and an absolute forward current of 1 A with 760 V of breakdown voltage (Diameter = 0.1 cm) were achieved on 20 and 8 µm epi-Ga2O3, respectively. The recovery characteristics for Ga2O3 FPET Schottky diode switching from forward current of 1 A and 0.3 A to reverse off-state voltage of -300 V and -900 V with recovery time (trr) of 60 ns and 81 ns were demonstrated on diodes with drift layers thickness of 8 µm and 20 µm with 4.4 × 1015 cm-3 and 2.0 x 1015 cm-3 Si-doped epi-Ga2O3 layer, respectively. There was no significant temperature dependence of trr up to 150°C. These results are an important milestone towards the applications of Ga2O3 vertical Schottky rectifiers in high power device and high-speed switching technologies.

Electrical properties of vertical GaN Schottky diodes on Ammono-GaN substrate

We report on electrical properties of vertical n-GaN high voltage Schottky diodes (SBDs) grown by two different techniques: Metal Organic Chemical Vapor Deposition (MOCVD) and Hydride Vapor Phase Epitaxy (HVPE) on highly-conductive n-type Ammono-GaN substrate. The thermionic emission (TE) current model has been applied for diodes parameters analysis. The fabricated SBDs exhibited a breakdown voltage of 670 V and 220 V, barrier height of 1.05 eV and 0.92 eV, ideality factor of 1.65 and 1.42 and series resistance of 440 Ω and 12 Ω for HVPE and MOCVD samples, respectively. Finally, we demonstrate preliminary point defects analysis for both types of the samples.

High Breakdown Strength Schottky Diodes Made from Electrodeposited ZnO for Power Electronics Applications

The synthesis of ZnO films by optimized electrodeposition led to the achievement of a critical electric field of 800 kV/cm. This value, which is 2–3 times higher than in monocrystalline silicon, was derived from a vertical Schottky diode application of columnar-structured ZnO films electrodeposited on platinum. The device exhibited a free carrier concentration of 2.5 × 1015 cm–3, a rectification ratio of 3 × 108, and an ideality factor of 1.10, a value uncommonly obtained in solution-processed ZnO. High breakdown strength and high thickness capability make this environment-friendly process a serious option for power electronics and energy harvesting.

Implementation of a 900 V Switching Circuit for High Breakdown Voltage β-Ga2O3 Schottky Diodes

This paper presents a switching circuit for high breakdown-voltage Ga2O3 vertical Schottky rectifiers. Field-plated edge-terminated (FPET) vertical Schottky diodes were fabricated on a 20-μm thick Si-doped n-type Ga2O3 drift layer which was grown on the 650-μm thick β-Ga2O3 substrate via halide vapor phase epitaxy (HVPE). The measured reverse recovery time of the proposed Ga2O3 Schottky diode was 81 ns when switched to a reverse bias voltage of −900 V. The implementation of a switching circuit with the novel Ga2O3 diode is the first demonstrated at such a high switching voltage. This paper also provides insights for the practical implementation of the Ga2O3 vertical Schottky rectifiers from device fabrication to circuit design.

High-performance quasi-vertical GaN Schottky diode with low turn-on voltage

In this letter, we demonstrate high performance GaN vertical Schottky diode on sapphire substrate. With optimized device structure and adopting low dislocation patterned sapphire substrate (PSS), a high DC performance with low turn-on voltage of 0.45 V, on-resistance of 0.084 mΩ cm2 and breakdown voltage above 100 V is achieved at a 6 × 100 μm2 anode size. Meanwhile, two types of GaN Schottky barrier diode (SBD) with different anode area were fabricated to investigate its influence on device characteristics. We have observed a larger current density and smaller leakage current with reducing the anode size, contributing to a more compact design for cost reduction.

Vertical and Lateral GaN Power Devices Enabled by Engineered GaN Substrates

The material and device performance of GaN layers on large diameter (150mm-200mm) engineered substrates was assessed. Vertical Schottky diode structures and lateral P-N junction gated field effect transistors were used as the device test vehicles. Vertical devices formed by substrate removal exhibited rectifying behavior and reasonable blocking performance, while lateral transistors exhibited excellent gate control and high current density.

(Invited) Current-Induced Degradation in Bulk GaN Vertical Schottky Diodes

The recent availability of high quality bulk GaN substrates with low threading dislocation density has made vertical power device structures an attractive possibility. Due to the low probability of a threading dislocation occurring within the active area of devices grown upon bulk GaN, reliability is driven by bulk or surface effects. Past work upon the reliability of Ni-GaN Schottky interfaces has suggested that interdiffusion of the Ni into the GaN can occur under thermal stress, adversely affecting the effective energy height of the barrier and increasing the ohmic nature of the interface. Conditions similar to such thermal stressing can be found at typical operating points in high current power devices used in power electronic applications. Our work examines the influence of high current density stress upon the reliability of vertical bulk GaN Schottky diodes. The vertical diodes studied were fabricated with Pd Schottky metallization with an Au ohmic overlayer. To study the effects of surface chemistry, reliability is compared between devices fabricated with different acidic and basic surface preparations, using HCl and KOH respectively. The fabricated devices were subject to life testing under varying levels of constant current density, up to 10 kA/cm^2. The lifetesting system was designed as a stress-measure-stress system, allowing for the evaluation of device parameters in-situ during testing. Electrical parameters indicating the state of the Schottky barrier were evaluated continuously during the measurement points of testing. In addition, a measurement of barrier inhomogeneity, evaluated using the Tung model, was also used as an indication of the condition of the Schottky interface. The microstructure of the interface before and after stress was examined using S/TEM imaging of representative lamellae samples of the stressed and unstressed devices. EDS imaging was used to determine the degree of diffusion between the Schottky metallization and the GaN substrate. Results of microstructure imaging are correlated with the electrical measurements taken to determine the responsible mechanisms for device degradation.

Leakage current reduction of vertical GaN junction barrier Schottky diodes using dual-anode process

The origin of the leakage current of a trench-type vertical GaN diode was discussed. We found that the edge of p-GaN is the main leakage spot. To reduce the reverse leakage current at the edge of p-GaN, a dual-anode process was proposed. As a result, the reverse blocking voltage defined at the leakage current density of 1 mA/cm2 of a vertical GaN junction barrier Schottky (JBS) diode was improved from 780 to 1,190 V, which is the highest value ever reported for vertical GaN Schottky barrier diodes (SBDs).

Barrier Inhomogeneity of Ni Schottky Contacts to Bulk GaN

Gallium nitride (GaN) is a promising candidate for high‐power and high‐frequency devices. To date, the lack of large area bulk GaN materials of reasonable cost and quality has limited the technology almost completely to lateral devices. However, vertical structures are attractive to obtain a higher current density and a reduced device size. In this work, the electrical behavior of a Ni/Au Schottky barrier on bulk GaN material is studied, using vertical Schottky diodes. The forward current–voltage characteristics of the diodes reveal a temperature dependence of both the ideality factor (n) and of the Schottky barrier height (ΦB). The ideal value of the barrier of 1.72 eV extrapolated at n = 1 is in agreement with the results obtained by capacitance–voltage measurements. A nanoscale electrical analysis performed by conductive atomic force microscopy (C‐AFM) allow to visualize the barrier height inhomogeneity and to correlate the current distribution to the surface morphology of the material. The barrier inhomogeneity explains the temperature behavior of ideality factor and barrier height determined by the macroscopic diodes. Preliminary structural analyses carried out by transmission electron microscopy (TEM) of the metal semiconductor interface revealed a typically flat Au/Ni bilayer structure, the Ni layer being epitaxial to GaN, with some mosaicity.

The effects of localized tail states on charge transport mechanisms in amorphous zinc tin oxide Schottky diodes

Temperature-dependent current–voltage measurements were performed on vertical Schottky diodes made with solution-processed amorphous zinc tin oxide (a-ZTO) semiconductor and palladium rectifying contacts. Above 260 K, forward bias electron transport occurs via thermionic emission over an inhomogeneous, voltage-dependent Schottky barrier with = 0.72 eV, σ0 = 0.12 eV, and A* = 44 A cm−2 K−2, where and are the mean potential barrier and its standard deviation at zero bias, respectively, and A* is Richardson’s constant. For large currents, the series ohmic resistance of the bulk semiconductor dominates. At temperatures below 260 K, less carriers are excited from localized states below the conduction band edge, and space-charge-limited current (SCLC) dominates. The exponential tail density of states parameters extracted for a-ZTO are gtc = 1.34 × 1019 cm−3 eV−1 and kTt = 26 meV. The intermediate tail state density in a-ZTO, less than that of amorphous silicon and greater than that of amorphous indium gallium zinc oxide, allows for experimental observation of a temperature-dependent transition of bulk charge transport mechanisms in strong forward bias from semiconductor-like ohmic conduction near room temperature to insulator-like SCLC at lower temperatures. In reverse bias, the same tail states lead to modified Poole–Frenkel emission, reducing the leakage current. The frequency response of a half-wave rectifier and diode impedance spectroscopy confirm that the Schottky diode cut-off frequency is above 1 MHz.

(Invited) Vertical GaN Devices Enabled By Selective Area P-Type Doping

A key element for enabling high performance vertical GaN power electronic devices is the capability to realize selective area p-type doping. The ability to arbitrarily define p-type regions through ion implantation eliminates the need for epitaxial regrowth on etched surfaces, which is currently a well-known technological roadblock. However, activation of implanted Mg is also a challenge, since activation of the Mg acceptors requires annealing at temperatures above the thermodynamic stability limits of GaN in atmosphere. Implementing the symmetric multi cycle rapid thermal annealing (SMTRA) technique has been shown to activate up to ~10% of the implanted Mg dopant atoms. This technique includes a temporary thermally stable capping layer, annealing in a nitrogen overpressure, and performing a well-optimized annealing temperature profile including multiple spike anneals. Vertical GaN junction barrier Schottky (JBS) diodes and Schottky barrier diodes (SBDs) with implanted junction termination extension (JTE) are demonstrated using the SMRTA process, as are process module development toward trench MOSFET devices.

Diamond Schottky diodes operating at 473 K

In this paper, we present current-voltage characteristics of vertical and pseudo-vertical Diamond Schottky diodes operating up to 473 K. The functionality rate is greater than 75% for each samples. For vertical diodes, current density at 473 K reaches 488 A/cm², while it is greater than 1000 A/cm² for pseudo-vertical diodes. Under reverse bias, the leakage current is less than 10−7 A/cm² at 50 V for all functional diodes. However, the high barrier height and high non-ideality factor observed are probably caused by high charges at the Diamond/Schottky contact interface. This article emphasizes the high reproducibility of the characteristics and the functionality rate at 473 K.

Modeling and Characterization of Vertical GaN Schottky Diodes With AlGaN Cap Layers

A new gallium nitride (GaN) Schottky device structure suitable for power electronic applications is discussed. A GaN Schottky diode with an ultrathin AlGaN cap layer was fabricated using an Ni/Au metal stack as the Schottky electrode. ${C}$ – ${V}$ measurements at various temperatures were used to calculate a barrier height of 0.65 V with a free electron concentration of $5 \times 10^{15}$ cm $^{-3}$ both of which appear temperature independent. A forward conduction model based on a thermionic emission–diffusion process with tunneling through the AlGaN barrier was developed and compared favorably to experimental data. A reverse conduction model utilizing thermionic field emission (TFE) with a triangular energy barrier is presented and then improved upon with a scaling factor that modifies the barrier thickness. This TFE model compares more favorably with the experimental data than the standard thermionic emission model typically used in Schottky diodes. Both the forward conduction and reverse conduction characteristics were assessed at room temperature and elevated temperature. The model can be used to predict how the physical parameters of the device affect its ${I}$ – ${V}$ characteristics.

On the laser lift-off of lightly doped micrometer-thick n-GaN films from substrates via the absorption of IR radiation in sapphire

The intense absorption of CO2 laser radiation in sapphire is used to separate GaN films from GaN templates on sapphire. Scanning of the sapphire substrate by the laser leads to the thermal dissociation of GaN at the GaN/sapphire interface and to the detachment of GaN films from the sapphire. The threshold density of the laser energy at which n-GaN started to dissociate is 1.6 ± 0.5 J/cm2. The mechanical-stress distribution and the surface morphology of GaN films and sapphire substrates before and after laser lift-off are studied by Raman spectroscopy, atomic-force microscopy, and scanning electron microscopy. A vertical Schottky diode with a forward current density of 100 A/cm2 at a voltage of 2 V and a maximum reverse voltage of 150 V is fabricated on the basis of a 9-μm-thick detached n-GaN film.

Vertical GaN Junction Barrier Schottky Diodes

Vertical GaN junction barrier Schottky (JBS) diodes are demonstrated. The JBS p-type grid was formed by Mg-implantation into a 10 μm thick unintentionally doped GaN homoepitaxial drift layer, grown by metal organic chemical vapor deposition (MOCVD). Then, symmetrical multi-cycle rapid thermal annealing (SMRTA) repaired implantation damage and activated the Mg ions. This process includes deposition of an AlN capping layer, annealing in a nitrogen overpressure, and rapid heating and cooling pulsed annealing. In addition, PiN diodes and Schottky barrier diodes (SBDs) were fabricated on the same substrate for comparison. The JBS diode demonstrates forward conduction characteristics dominated by the Schottky barrier (turn-on voltage ∼0.5 V), and reverse breakdown voltage comparable to the PiN diode (−610 V).

Mo1-xWxSe2-Based Schottky Junction Photovoltaic Cells.

We developed Schottky junction photovoltaic cells based on multilayer Mo1-xWxSe2 with x = 0, 0.5, and 1. To generate built-in potentials, Pd and Al were used as the source and drain electrodes in a lateral structure, and Pd and graphene were used as the bottom and top electrodes in a vertical structure. These devices exhibited gate-tunable diode-like current rectification and photovoltaic responses. Mo0.5W0.5Se2 Schottky diodes with Pd and Al electrodes exhibited higher photovoltaic efficiency than MoSe2 and WSe2 devices with Pd and Al electrodes, likely because of the greater adjusted band alignment in Mo0.5W0.5Se2 devices. Furthermore, we showed that Mo0.5W0.5Se2-based vertical Schottky diodes yield a power conversion efficiency of ∼16% under 532 nm light and ∼13% under a standard air mass 1.5 spectrum, demonstrating their remarkable potential for photovoltaic applications.

Particle size effects on the hydrogen sensing properties of Pd/ZnO Schottky contacts fabricated by sol–gel method

ZnO thin films grown on n-Si substrates using sol–gel spin coating method were annealed in Ar atmosphere at 450 °C, 550 °C and 650 °C temperatures. Three types of Pd/n-ZnO/n-Si/Ti/Al vertical Schottky diodes were fabricated using three types of ZnO films obtained by annealing at the aforementioned three different annealing temperatures for hydrogen gas sensing applications. Using thermal evaporation method, the Pd metals dots were deposited for the Schottky contacts on the annealed ZnO films while Ti and Al were sequentially deposited over the back side of the n-Si for forming the ohmic cathode contact of the diode. The XRD and SEM analyses showed that the structural and surface properties of the ZnO thin films were largely influenced by the annealing temperature. The grain size was observed to be increased with annealing temperature of the ZnO films. The increased grain size at higher annealing temperatures reduces the surface to volume ratio, number of nanoparticles in the ZnO films (and hence the number of Schottky barriers formed between a nanoparticle and Pd) and number of grain boundaries (due to merging of a number of smaller grains into a larger sized grain) which, in turn, affects the hydrogen sensing properties of the devices under consideration. This paper investigates the effects of grain size on the hydrogen sensing property, series resistance and barrier height of the Pd/ZnO film Schottky diodes in details. The highest hydrogen response was observed in the device containing the ZnO film annealed at 450 °C which was attributed to the largest surface to volume ratio owing to the smallest particle size in the ZnO film.

(Invited) DLTS Studies of Defects in n-GaN

Introduction There exist various defects in GaN depending on growth methods or growth conditions or substrates used for the epitaxial growth. There are point defects, such as vacancy-related defects, antisite defects, interstitials as well as line defects, i.e. dislocations. These affect the performance of GaN-based devices, since they create deep levels in the bandgap and act as traps and generation-recombination centers. Foreign atoms, such as carbon and iron, also create deep levels. It is important to characterize these defects and identify their origins to realize the high performance of GaN-based devices. Current collapse in AlGaN/GaN high electron mobility transistors is well known to be caused by trapping of carriers [1]. In this work, we present our results on the characterization of traps in Si-doped n-GaN grown by metal organic chemical vapor deposition (MOCVD) on different substrates, that is, sapphire, n+-GaN, SiC and Si [2]. Experimental Lateral and vertical Schottky diodes were fabricated using Pt/Au or Ni/Au as a Schottky contact and Ti/Al/Ni/Au as an ohmic contact for n-GaN on sapphire, Si and SiC substrates and for n-GaN on n+-GaN substrates, respectively. Carrier concentrations determined from capacitance-voltage measurements at room temperature are in the range from 1016 to 1017 cm-3. Deep level transient spectroscopy (DLTS) using bias pulses has been applied to estimate electron traps for fabricated Schottky diodes. Minority carrier transient spectroscopy (MCTS) using above-band-gap light pulses has been used to characterize hole traps. Results and Discussion Temperature-scan DLTS and MCTS have been performed in the temperature range from 90 to around 400 K. DLTS measurements detected four electron traps labeled E1 (Ec-0.24 eV), E3 (Ec-0.57 eV), E6 (Ec-0.40 eV) and E7 (Ec-0.73 eV). E1 and E3 might be ascribed to VGa-VN pairs and NGa antisite defects, respectively. E6 and E7 are observed for n-GaN on SiC and Si, suggesting their correlation to dislocation-related defects. MCTS measurements detected three hole traps labeled H1 (Ev+0.86 eV), H2 (Ev+0.25 eV) and H3 (Ev+0.25 eV). Trap E3 and H1 concentrations are as high as 1016 cm-3 and show a large variation of trap concentration on each wafer. Moreover, trap H1 concentration increases in n-GaN intentionally doped with carbon, suggesting its correlation to carbon-related defects, possibly in addition to VGa-related defects. We have studied a distribution of trap E3 and H1 concentration for a quarter of 2-inch n-GaN on n+-GaN using isothermal DLTS and MCTS measurements at room temperature, respectively. A variation of trap E3 concentration over four orders of magnitude is found in the range from ~1012 to ~1016 cm-3 with the average concentration of 4.6x1014 cm-3, while trap H1 shows a relatively small variation in the range from~1015 to ~1016 cm-3 with the average concentration of 5.9x1015 cm-3. Average trap concentration of trap H1 is higher in n-GaN doped with carbon of 6x1016 cm-3 and is found to be 4.2x1016 cm-3. It is thought that the increased concentration of trap H1 in carbon-doped GaN corresponds to the concentration of carbon-related defects. In this context, we will present a method to distinguish between VGa-related and carbon-related defects with similar thermal emission activation energies by a combination of MCTS and optical deep level transient spectroscopy (ODLTS) using below-band-gap light pulses. Further, we will discuss on the identification of these traps by varying MOCVD growth conditions, namely, V/III ratios, growth pressures and growth temperatures. Acknowledgments This work has been performed as an MEXT-Supported Program for the Strategic Research Foundation at Private Universities (2010-2014).

In Situ Chemical Modification of Schottky Barrier in Solution-Processed Zinc Tin Oxide Diode

Here we present a novel in situ chemical modification process to form vertical Schottky diodes using palladium (Pd) rectifying bottom contacts, amorphous zinc tin oxide (Zn-Sn-O) semiconductor made via acetate-based solution process, and molybdenum top ohmic contacts. Using X-ray photoelectron spectroscopy depth profiling, we show that oxygen plasma treatment of Pd creates a PdOx interface layer, which is then reduced back to metallic Pd by in situ reactions during Zn-Sn-O film annealing. The plasma treatment ensures an oxygen-rich environment in the semiconductor near the Schottky barrier, reducing the level of oxygen-deficiency-related defects and improving the rectifying contact. Using this process, we achieve diodes with high forward current density exceeding 10(3)A cm(-2) at 1 V, rectification ratios of >10(2), and ideality factors of around 1.9. The measured diode current-voltage characteristics are compared to numerical simulations of thermionic field emission with sub-bandgap states in the semiconductor, which we attribute to spatial variations in metal stoichiometry of amorphous Zn-Sn-O. To the best of our knowledge, this is the first demonstration of vertical Schottky diodes using solution-processed amorphous metal oxide semiconductor. Furthermore, the in situ chemical modification method developed here can be adapted to tune interface properties in many other oxide devices.

(Invited) Vertical GaN High Voltage Transistors: Comparison with SiC Switches

Wide bandgap (WBG) semiconductor high-voltage power switching devices, especially those made on silicon carbide (SiC) and gallium nitride (GaN), promise transformative advances in electrical power switching systems because of superior electrical and thermal properties of these materials compared to the semiconductor silicon [1]. Both SiC and GaN semiconductors contain a high density of crystal defects and the role of defects on the performance and reliability of electrical power switching devices under extreme operating environment is not clear. The approach and results for achieving wide bandgap semiconductor (GaN) based high voltage “vertical” switches is reported. The GaN and the related ternaries, AlGaN and InGaN are the materials of choice due to their superior properties. While the performance of the current generation of GaN devices is limited by material and reliability issues, the promise still remains an elusive goal. The results reported in the present work address the issues of performance and reliability for future GaN and related compound power devices, and will enable the development a new class of devices based on V-HEMTS and Trench HFETs to exceed the state of the art of 2.5 kV for silicon and SiC devices for blocking voltages up to 10 kV. We report results which include the design, fabrication and testing of structures exploiting HEMT GaN/AlGaN structures as well as a new and unique GaN Trench MOS design shown in Figure 1. In this comparison, we review the key reliability issues facing SiC High Voltage MOSFETS, as well as the role of threading edge dislocations and threading screw dislocations affecting SiC MOSFET reliability. These issues are compared to similar defect related limitations for GaN vertical devices as well. Material-device-performance correlation methodology ensures that the reliability is designed in through the physics of failure approach. The research results reported also assesses other novel structures with blocking voltages in excess of 10kV as well as the evaluation of the reliability of these devices under system environments. We note that crystallographic defects when present in active areas of SiC-based devices have a negative influence on device performance, reliability and reproducibility. Micropipes are well-known as device killers while the detrimental influence of Basel Plane Dislocations (BPDs) on device performance is also established [2]. For the present work we have investigated a vertical 4H-SiC Junction Barrier Schottky (JBS) diode where a slightly higher doped n-type buffer layer is used to constrict the spreading of the space-charge region beyond the lightly doped n- - type drift-region. The diode was subjected to increasing reverse voltage stress starting at the rated 600V. The reported experimental data for high-voltage SiC semiconductor strongly suggests that material defects have profound impact on its characteristics under extreme environments. Since GaN semiconductor has even higher density of material defects, this problem may be further exacerbated. REFERENCES [1] K. Shenai et al, IEEE Trans. Electron Devices 36, 1811-1823, 1989. [2] R. L. Myers-Ward, D. K. Gaskill, R. S. Stahlbush, N. A. Mahadik, V. D. Wheeler, L. O. Nyakiti, and C. R. Eddy, Jr., Electro Chemical Society Transactions, vol. 50, no. 3, ISBN 978-1-62332-002-7, pp. 103-108, Oct. 2012.