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This paper presents tables of key thermoelectric properties, which define thermoelectric conversion efficiency, for a wide range of inorganic materials. The twelve families of materials included in these tables are primarily selected on the basis of well established, internationally-recognized performance and promise for current and future applications: tellurides, skutterudites, half Heuslers, Zintls, Mg-Sb antimonides, clathrates, FeGa3-type materials, actinides and lanthanides, oxides, sulfides, selenides, silicides, borides and carbides. As thermoelectric properties vary with temperature, data are presented at room temperature to enable ready comparison, and also at a higher temperature appropriate to peak performance. An individual table of data and commentary are provided for each family of materials plus source references for all the data., National Science Foundation; UK Engineering and Physical Sciences Research Council (EPSRC)

In this letter, novel heterostructure p-i-n GaN avalanche photodiodes (APDs) with p-type In0.05Ga0.95N layer are proposed and analyzed through Silvaco Atlas simulations. The introduction of the In0.05Ga0.95N layer generates a negative polarization charge at the p-In0.05Ga0.95N/i-GaN heterojunction interface via the piezoelectric polarization effect. Three times higher hole concentration in the p-In0.05Ga0.95N layer is obtained due to the smaller activation energy of the Mg dopant. Induced polarization charge and increased hole concentration work together to reduce the voltage drop in the p-In0.05Ga0.95N layer and enhance the electric field intensity in the i-GaN layer. The calculated results show that the heterostructure APD demonstrates a reduced operating voltage of more than 26 V and an improved multiplication gain by an order of magnitude in comparison to the conventional one.

ZnOTe compounds were grown by DC magnetron cosputtering from pure Tellurium (Te) and Zinc (Zn) cathodes in O2/Ar atmosphere. The applied power on the Zn target was constant equal to 100 W, while the one applied on the Te target took two values, i.e., 5 W and 10 W. Thus, two sample series were obtained in which the variable parameter was the distance from the Te targets to the substrate. Sample compositions were determined by Rutherford Backscattering Spectroscopy (RBS) experiments. Structural analysis was done using X-Ray diffraction (XRD) spectrometry and the growth of the hexagonal w-ZnO phase was identified in the XRD spectra. RBS results showed high bulk homogeneity of the samples forming ZnOTe alloys, with variable Te molar fraction (MF) ranging from 0.48–0.6% and from 1.9–3.1% for the sample series obtained at 5 W and 10 W, respectively. The results reflect great differences between the two sample series, particularly from the structural and optical point of view. These experiments point to the possibility of Te doping ZnO with the permanence of intrinsic defects, as well as the possibility of the formation of other Te solid phases when its content increases. The results and appreciable variations in the band gap transitions were detected from Photoluminescence (PL) measurements., This work was supported by the Ministerio de Ciencia, Innovación y Universidades of Spain through the Project RTI2018-095137-B-I00.

Sb anion-substituted gallium nitride films were fabricated by radio frequency reactive sputtering with single Sb-containing cermet targets with different Sb contents under Ar/N2 atmosphere. n-type GaN films with electron concentration of (1.40 &plusmn, 0.1) &times, 1017 cm&minus, 3 inverted to p-type Sb-GaN with hole concentration of (5.50 &plusmn, 0.3) &times, 3. The bandgap energy of Sb anion-added Sb-GaN films decreased from 3.20 to 2.72 eV with increasing Sb concentration. The formation of p-type Sb-GaN is attributed to the formation of Ga vacancy at higher Sb concentration. The coexistence of Sb at the Ga cation site and N anion site is an interesting and important result, as GaNSb had been well developed for highly mismatched alloys. The hetero-junction with p-type Sb-GaN/n-Si diodes was all formed by radio frequency (RF) reactive sputtering technology. The electrical characteristics of Sb-GaN diode devices were investigated from &minus, 20 to 20 V at room temperature (RT).

A method of Al2O3 deposition and subsequent post-deposition annealing (Al2O3-PDA) was proposed to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates, which were fabricated using Ge condensation by dry oxidation. The effect of Al2O3-PDA on defect passivation was clarified by surface analysis and electrical evaluation. It was found that Al2O3-PDA could not only suppress the surface reaction during Al-PDA in our previous work [Yang H, Wang D, Nakashima H, Hirayama K, Kojima S, Ikeura S. Defect control by Al-deposition and the subsequent post-annealing for SiGe-on-insulator substrates with different Ge fractions. Thin Solid Films 2010; 518: 2342–5.], but could also effectively passivate p-type defects generated during Ge condensation. The concentration in the range of 1016–1018 cm−3 for defect-induced acceptors and holes in Ge-rich SGOI drastically decreased after Al2O3-PDA. As a result of defect passivation, the electrical characteristics of both back-gate p-channel and n-channel metal–oxide-semiconductor field-effect transistors fabricated on Ge-rich SGOI were greatly improved after Al2O3-PDA.

We report on the growth of Li-Ni codoped p-type ZnO thin films using pulsed laser deposition. Two mole percent Li monodoped ZnO film shows highly insulating behavior. However, a spectacular decrease in electrical resistivity, from 3.6 � 10 3 to 0.15 ? cm, is observed by incorporating 2 mol % of Ni in the Lidoped ZnOfilm.Moreover, the activation energy drops to 6meV from78 meV with Ni incorporation in Li:ZnO lattice. The codoped [ZnO:(Li, Ni)] thin film shows p-type conduction with room temperature hole concentration of 3.2 � 10 17 cm -3. Photo-Hall measurements show that the Li-Ni codoped p-ZnOfilm is highly stable even with UV illumination. XPS measurements reveal that most favorable chemical state of Ni is Ni 3+ in (Li, Ni): ZnO. We argue that these Ni 3+ ions act as reactive donors and increase the Li solubility limit. Codoping of Li, with other transitional metal ions (Mn, Co, etc.) in place of Ni could be the key to realize hole-dominated conductivity in ZnO to envisage ZnO-based homoepitaxial devices. � 2011 American Chemical Society.

Here, controlled p-type doping of poly(2-methoxy-5-(20-ethylhexyloxy)- pphenylene vinylene) (MEH-PPV) deposited from solution using tetrafluorotetracyanoquinodimethane (F4-TCNQ) as a dopant is presented. By using a co-solvent, aggregation in solution can be prevented and doped films can be deposited. Upon doping the current-voltage characteristics of MEH-PPVbased hole-only devices are increased by several orders of magnitude and a clear Ohmic behavior is observed at low bias. Taking the density dependence of the hole mobility into account the free hole concentration due to doping can be derived. It is found that a molar doping ratio of 1 F4-TCNQ dopant per 600 repeat units of MEH-PPV leads to a free carrier density of 441022m 3. Neglecting the density-dependent mobility would lead to an overestimation of the free hole density by an order of magnitude. The free hole densities are further confirmed by impedance measurements on Schottky diodes based on F4-TCNQ doped MEH-PPV and a silver electrode. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.

An analytical model of drain current of Si/SiGe heterostructure p-channel MOSFETs is presented. A simple polynomial approximation is used to model the sheet carrier concentration (p/sub s//sup H/) in the two-dimensional hole gas at the Si/SiGe interface. The interdependence of p/sub s//sup H/ and the hole concentration at the Si/SiO/sub 2/ interface (p/sub s//sup S/) is taken into account in the model, which considers current flow at both the Si/SiGe and the Si/SiO/sub 2/ interfaces. This model is applicable to compressively strained SiGe buried-channel heterostructure PMOSFETs as well as tensile-strained surface-channel PMOSFETs. The model has been implemented in SABER, a circuit simulator. The results from the model show an excellent agreement with the experimental data.

The effect of precursors vapour stoichiometry on the morphological, structural and electrical properties of nominally undoped ZnTe grown on (100)GaAs by metalorganic vapour phase epitaxy is reported. The epilayers were grown at 350 °C using dimethylzinc (Me2Zn) and di-isopropyltelluride, varying their molar flow rate ratios (MFRs) between 0.17 and 3.10. Growth in nearly stoichiometric (MFR = 1.03) conditions results in best surface morphology, while samples grown in Te-rich conditions (MFR > 1.7) showed micron-size hollow defects (with surface densities up to ∼106 cm–2) elongated in one of the 〈011〉 in-plane directions. The defects are associated to a local structural disorder of the material, ascribed to the formation of a Ga2Te3 extrinsic phase at the ZnTe/GaAs interface. Ohmic contacts to p -ZnTe epilayers were prepared by tungsten evaporation and annealing at 350 °C. The RT hole concentration in the epilayers varies almost linearly with Me2Zn molar flow between 2 × 1015 cm–3 and 5 × 1016 cm–3. Temperature-dependent Hall measurements performed on samples grown at MFR ≤ 1.03 demonstrate that the material p-type conductivity originates from a single acceptor centre with an ionisation energy between 94.7 meV and 118 meV, its concentration being in the 1016 cm–3 range and slowly increasing with Me2Zn flow. We ascribe this acceptor to a complex formed by a substitutional carbon atom on a Te site and a donor on a nearest neighbor site (CTe-DZn), the donor impurity being further identified as Ga diffusing from the substrate. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The authors present results of research and development of mid-infrared photodiodes based on antimonide solid solutions operating at room temperature in the spectral range of 1.5-4.8 /spl mu/m. A new physical approach to the design of long-wavelength photodiodes is proposed by using type II broken-gap heterostructures grown by liquid-phase epitaxy on GaSb substrates. The choice of sequence of the narrow-gap and wide-gap layers in the GaSb/InGaAsSb/GaInAsSb and GaSb/InGaAsSb/AlGaAsSb heterostructures allows one to vary the band energy diagram and barrier heights on the interface. Electrical and photoelectrical parameters of three kinds of devices were studied. A detectivity of D/sup *//sub /spl lambda//=4.1/spl times/10/sup 8/ cmHz/sup 1/2//W was found at /spl lambda/=4.7 /spl mu/m, T=300 K.

Due to the limitation of the hole injection, p-type doping is essential to improve the performance of InGaN/GaN multiple quantum well light-emitting diodes (LEDs). In this work, we propose and show a depletion-region Mg-doping method. Here we systematically analyze the effectiveness of different Mg-doping profiles ranging from the electron blocking layer to the active region. Numerical computations show that the Mg-doping decreases the valence band barrier for holes and thus enhances the hole transportation. The proposed depletion-region Mg-doping approach also increases the barrier height for electrons, which leads to a reduced electron overflow, while increasing the hole concentration in the p-GaN layer. Experimentally measured external quantum efficiency indicates that Mg-doping position is vitally important. The doping in or adjacent to the quantum well degrades the LED performance due to Mg diffusion, increasing the corresponding nonradiative recombination, which is well supported by the measured carrier lifetimes. The experimental results are well numerically reproduced by modifying the nonradiative recombination lifetimes, which further validate the effectiveness of our approach. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) Published version

The recombination centre that emerges in boron- and oxygen-containing silicon was thought to be a complex of a substitutional boron atom Bs and an oxygen dimer O2. However in material co-doped with boron and phosphorus, the degradation parameters were reported to correlate with the hole concentration p rather than with the boron concentration. In the present work, the temperature dependence of the Hall Effect was measured in co-doped and reference samples and the concentrations of isolated acceptors Na and of donors Nd were deduced. The value of Na was found to be substantially larger than p and close to the expected total concentrations of boron. This result clearly shows that the reported correlation of the degradation with p implies a lack of correlation with Na. Such a behaviour is accounted for by a model based on formation of BiO2 complexes (involving an interstitial boron atom Bi rather than Bs): the grown-in concentration of this species is proportional to p and independent of Na.

Magnetically doped Si and Ge nanowires have potential application in future nanowire spin-based devices. Here, we report a supercritical fluid method for producing single crystalline Mn-doped Ge nanowires with a Mn-doping concentration of between 0.5-1.0 atomic % that display ferromagnetism above 300 K and a superior performance with respect to the hole mobility of around 340 cm(2)/Vs, demonstrating the potential of using these nanowires as building blocks for electronic devices.

Hole conducting, optically transparent Cu2O thin films on glass substrates have been synthesized by vacuum annealing (5�10-6 mbar at 700 K for 1 hour) of magnetron sputtered (at 300 K) CuO thin films. The Cu2O thin films are p-type and show enhanced properties: grain size (54.7 nm), optical transmission 72% (at 600 nm) and Hall mobility 51 cm2/Vs. The bulk and surface Valence band spectra of Cu2O and CuO thin films are studied by temperature dependent Hall effect and Ultra violet photo electron Spectroscopy (UPS). CuO thin films show a significant band bending downwards (due to higher hole concentration) than Cu2O thin films. � 2015 Author(s).

The low p-type doping efficiency of the p-GaN layer has severely limited the performance of InGaN/GaN light-emitting diodes (LEDs) due to the ineffective hole injection into the InGaN/GaN multiple quantum well (MQW) active region. The essence of improving the hole injection efficiency is to increase the hole concentration in the p-GaN layer. Therefore, in this work, we have proposed a hole modulator and studied it both theoretically and experimentally. In the hole modulator, the holes in a remote p-type doped layer are depleted by the built-in electric field and stored in the p-GaN layer. By this means, the overall hole concentration in the p-GaN layer can be enhanced. Furthermore, the hole modulator is adopted in the InGaN/GaN LEDs, which reduces the effective valance band barrier height for the p-type electron blocking layer from ∼332 meV to ∼294 meV at 80 A/cm2 and demonstrates an improved optical performance, thanks to the increased hole concentration in the p-GaN layer and thus the improved hole injection into the MQWs. ASTAR (Agency for Sci., Tech. and Research, S’pore) Published version

An experimental study of the VPE growth of GaAs at 1 023 K from the AsH 3-HCl-Ga-H 2 system yields for the dependence of the hole concentration on the technological parameters : p (300 K) ∼ p HCl·p-1GaCl·p1/2AsH3·p Zn. It is concluded that the process takes place under non equilibrium conditions. The PL intensity depends distinctly on the preparation conditions but does not fit a simple model.

Single phase bulk Tl2223 samples were prepared in the Tl 2−x z Ba 2 Ca 2+x Cu 3 O 10−y system with x =0.0 to 0.4. Wet chemical analysis shows that all samples are both Tl and O deficient. The T c is found to increase with increasing hole concentration. Ultraviolet photoemission spectroscopic (UVPES) studies of the “as synthesized” Tl 2− x − z Ba 2 Ca 2+ x Cu 3 O 10− y system have been carried out. No shifts in binding energy of valence band features are observed. Instead, doping of Ca at the Tl site creates new electronic states near the Fermi level. Tl 4f core level X-ray photoelectron spectroscopic (XPS) studies show a systematic decrease in BE with x . Systematic changes in the Cu 2p core level spectra are also observed. Possible changes in the valence band structure are suggested.