Conductive isostructural compounds
Patent ReferencesInventorsAssigneeApplicationNo. 10703026 filed on 11/06/2003US Classes:252/62.3T, Thermoelectric252/519.4, Sulfur, selenium, or tellurium containing136/238, Chalcogenide containing (S, O, Te, Se)136/239, Group IV element containing (C, Si, Ti, Ge, Zr, Sn, Hf, Pb)136/240, Group V metal containing (V, As, Nb, Sb, Ta, Bi)136/241, Group IB metal containing (Cu, Ag, Au)136/259, With concentrator, housing, cooling means, or encapsulated136/261, Silicon or germanium containing136/264, Selenium or tellurium containing257/65, Non-single crystal, or recrystallized, material containing non-dopant additive, or alloy of semiconductor materials (e.g., Ge x Si 1- x, polycrystalline silicon with dangling bond modifier)257/431, Light257/467, Temperature257/613, INCLUDING SEMICONDUCTOR MATERIAL OTHER THAN SILICON OR GALLIUM ARSENIDE (GAAS) (E.G., PB X SN 1-X TE)250/338.4, Semiconducting type250/370.14Particular detection structure (e.g., MOS, PIN)ExaminersPrimary: Koslow, C. MelissaAttorney, Agent or FirmInternational ClassH01L 29/15DescriptionFIELD OF THE INVENTION This invention relates generally to new compounds exhibiting crystal lattice morphologies and, more particularly, to conductive compounds having NaCl-type cubic crystal lattice structures. BACKGROUND OF THE INVENTION Semiconductor materials are at the core of current technological infrastructure and continuing advancements. Various semiconductors enable many technologies. For example, Si and Ge enable high speed computing, GaAs, InSb and their derivativesenable optoelectronics and communication devices, Si and GaAs are the vital components of solar energy converters, GaN and GaAs alloys enable solid state lasers, Bi2Te.sub.3 alloys enable thermoelectric cooling, and PbS, PbSe and HgCdTe are used inmedium and long wavelength radiation detection. Semiconductor materials used in solid state lasers, photovoltaic cells, optoelectronic devices and radiation detection, for example, must not only be excellent electronic conductors, but also have the appropriate energy band configuration or"band gap" for those applications. As more than one material is used in layers, the difference in the band gap between the various semiconductor materials used is also critical. For example, photovoltaic cells can use two semiconductor materials toproduce a rectifying heterojunction. The advantages of utilizing this design include the ability to choose materials with properties appropriate for each component of the device and the reduced necessity for compromise with the property requirements ofother components of the device. An example of this is the use of a wide band gap "window" semiconductor material as a barrier layer on a more narrow band gap "absorber" semiconductor material. The amount of radiation absorbed and therefore theelectrical current generated in the device, increases with the decreasing band gap width, while the diffusion potential obtainable within the device, and therefore the electrical voltage generated in the device, increases with band gap width. Thus, theabsorber material is chosen to maximize the solar radiation absorbed and affords a reasonable diffusion potential, while window material is chosen to absorb a minimum amount of solar radiation. Therefore, the closer the actual band gap to the desired,theoretical band gap of the semiconductor materials, the more efficient the photovoltaic cell. Many current semiconductor materials are limited in that they do not allow for fine adjustment of the band gap. Furthermore, some semiconductor materialscontain volatile elements causing changes in the composition of the materials and consequently unwanted changes in the band gap. In thermoelectric devices, it is also critical to have semiconductor materials that have specific properties. Such devices may be used for heating, cooling, temperature stabilization, power generation and temperature sensing. Modernthermoelectric coolers typically include an array of thermocouples. Thermoelectric devices are essentially heat pumps and power generators which follow the laws of thermodynamics in the same manner as mechanical heat pumps, refrigerators, or any other apparatus used to transfer heat energy. The efficiency of athermoelectric device is generally limited to its associated Carnot cycle efficiency reduced by a factor which is dependent upon the thermoelectric figure of merit (zT) of the materials used in fabrication of the thermoelectric device. The figure ofmerit represents the coupling between electrical and thermal effects in a material. The basic thermoelectric effects are the Seebeck and Peltier effects. The Seebeck effect is the phenomenon underlying the conversion of heat energy into electricalpower and is used in thermoelectric power generation. The complementary effect, the Peltier effect, is the phenomenon used in thermoelectric refrigeration and is related to heat absorption accompanying the passage of current through the junction of twodissimilar materials. While thermoelectric materials such as alloys of Bi2Te.sub.3, PbTe and BiSb were developed thirty to forty years ago, the efficiency of such thermoelectric devices remains relatively low at approximately five to eight percent energyconversion efficiency. Therefore it would be desirable to have semiconductor materials that are not only good conductors but have a range of band gaps to fit a wide number of applications. It would be further desirable to have materials in which the band gaps could beadjusted to give the desired band gap for the appropriate application. These materials should also be thermal and chemically stable. Furthermore, it would be desirable to have thermoelectric materials that have a high thermoelectric figure of merit. Use of such materials would produce thermoelectric devices with high efficiencies. SUMMARY OF THE INVENTION The present invention relates to new isostructural compounds having the general formula AnM.sub.mM'nO.sub.2n m where A is an alkali metal, such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), or cesium (Cs) or the transitionmetal silver (Ag) or thallium (TI) and mixtures thereof, M is lead (Pb), tin (Sn), germanium (Ge), calcium (Ca), strontium (Sr), barium (Ba), any divalent transition metal or mixtures thereof, M' is bismuth (Bi), antimony (Sb) or mixtures thereof, and Qis sulfur (S), selenium (Se), or tellurium (Te) and mixtures thereof. These compounds possess an NaCl-type cubic lattice crystal structure where A, M and M' occupy the Na sites and Q occupies the Cl (chlorine) sites. This family of compounds combineisotropic morphology, an advantageous property for device processing, with low thermal conductivity and widely ranged electrical conductivity. Further, certain properties such as the electrical properties of the compounds can be controlled by varyingthe values for n and m. The isostructural compounds of the present invention are therefore good candidates for semiconductor applications in thermoelectronic devices, detectors, and photovoltaic cells, by way of non-limiting example. Additional objects, advantages, and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of the crystal structure of AnPb.sub.mBi.sub.nO.sub.2n m; FIG. 2A is a graph showing the infrared absorption spectrum of K2PbBi.sub.2Se.sub.5; FIG. 2B is a graph showing the infrared absorption spectrum of KPb4BiSe.sub.6; FIG. 2C is a graph showing the infrared absorption spectrum of KPb8BiSe.sub.10; FIG. 2D is a graph showing the infrared absorption spectrum of PbSe; FIG. 3 is an illustration showing a multispectral sensor with a two-materials stacked structure; FIG. 4 is a graph showing the effect of increasing temperature on the resistivity of KPb8BiTe.sub.10; and FIG. 5 is a graph showing the effect of increasing temperature on the Seebeck coefficient of KPb8BiTe.sub.10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides new isostructural compounds having the general formula AnM.sub.mM'nO.sub.2n m where A is an alkali metal, such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) or the transitionmetals silver (Ag) or thallium (TI) and mixtures thereof, M is lead (Pb), tin (Sn), germanium (Ge), calcium (Ca), strontium (Sr), barium (Ba), any divalent transition metal or mixtures thereof, M' is bismuth (Bi), antimony (Sb) or mixtures thereof, and Qis sulfur (S), selenium (Se), or tellurium (Te) and mixtures thereof. The variables n and m can be any number greater than zero. Preferably, n and m are integers. While the variables n and m can theoretically be any integer, preferably, n and m are between 1 and 20. Additionally, the ratio of cations to anionspresent in the compounds of the present invention will preferably be 1:1. The compounds of the present invention can be synthesized utilizing at least two different groups of starting materials or from the pure elements themselves. According to one embodiment, the group of starting materials are A2Q, M, M' and Qand under another embodiment the group of starting materials are A2Q, M'2Q.sub.3, M and Q, wherein M and Q can be in the form of MQ as will be described below. In yet another embodiment, the pure elements, A, M, M' and Q, in the correctstoichiometric ratios can be used to synthesize the compounds of the present invention. A2Q can be prepared by reacting stoichiometric amounts of the elemental A (2 moles) with the elemental Q (1 mole) in liquid ammonia. When the reaction is complete, the ammonia is removed by evaporation at ambient temperature. The resultingproduct is dried and ground to give a fine homogeneous powder. M'2Q.sub.3 can be generally prepared by reacting stoichiometric amounts of elemental Bi or Sb (2 moles) and elemental Q (3 moles) at 800° C. for about 1-3 days at ambient pressure or optionally under a vacuum to reduce reactiontimes. Alternatively, bismuth telluride (Johnson Matthey/AESAR Group, Seabrook, N.H.) and bismuth selenide (Cerac, Inc, Milwaukee, Wis.) can be obtained commercially. MQ can be synthesized, for example, by thoroughly mixing stoichiometric amounts (1 mole each) of elemental Pb, Sn, Ge, Ca, Sr, Ba, or any divalent transition metal and Q and loading the mixture into a quartz tube at a residual pressure of lessthan 10-4 Torr. The mixture is then heated to 800° C. over a 24 hour period and the temperature maintained for an additional 24 hours. The mixture is then cooled by quenching in water and the resulting ingot is crushed to a fine powder. The powder is then reloaded into a quartz tube and heated to 800° C. over a 24 hour period. The temperature of the mixture is maintained at 800° C. for an additional 24 hours and then slowly cooled to 300° C. at a rate of about4° C./hr and subsequently to 50° C. over about 6 hours. The resulting ingots are ground to a fine powder prior to synthesis of the compounds of the present invention. Upon forming each of the compounds included in the groups of starting materials, the isostructural compounds of the present invention are synthesized by thoroughly mixing and loading the chosen starting materials into a carbon coated quartz orcapped graphite tube at a residual pressure less than 10-4 Torr, i.e., either the group of A2Q, M metal, M' metal and elemental Q or the group A2Q, M'2Q.sub.3 and MQ. The mixture is heated to 700° C. at a rate of about30° C./hr. After maintaining the temperature at 700° C. for approximately 3 days, the mixture is cooled to 300° C. at a rate of 5° C./hr followed by cooling to 50° C. in about 12 hours. The resulting product iswashed with degassed dimethylformamide and water in a nitrogen atmosphere. After further washing with diethyl ether and subsequent drying, the isostructural compounds of the present invention are obtained as shiny black chunks exhibiting the abovedescribed cubic phase. The compounds of the present invention can al be synthesized from the pure elements. The appropriate elements for the desired compound, A, M, M' and Q, are mixed together in the correct stoichiometric ratios and sealed in a quartz tube undervacuum, i.e., <10-3 Torr. The mixture is then heated in a direct flame until molten. Subsequent cooling of the melt yields the corresponding compound. To synthesize KSnBiSe3, by way of non-limiting example, 0.01 mole (0.39g) of potassium,0.01 mole (1.18 g) tin, 0.01 mole (2.09g) bismuth and 0.03 mole (2.37g) of selenium were mixed, placed in a quartz tube and sealed under vacuum at <10-3 Torr. The mixture was heated in a direct flame until molten and subsequently cooled to yieldthe desired product, KSnBiSe3. As noted above, the isostructural compounds of the present invention have a cubic crystal lattice structure of the same type as NaCl, wherein the cations (or metals) occupy the Na sites and the anions occupy the Cl sites. The cations, althoughdiffering in charge, are similar in size and tend to become randomly dispersed throughout the structure as shown in FIG. 1. This cubic crystal structure is independent of the values for n and m and depends only on the elements selected to form theisostructural compounds. A property of this cubic structure of the compounds of the present invention is a morphology of low anisotropy which is desirable for fabricating electronic and optical devices, by way of non-limiting example. The cubicstructure also gives rise to relatively high carrier mobilities and ease of crystal growth and processing. The compounds of the present invention also have relatively high melting point temperatures which are considered to be indicative of a high degreeof structural stability. The melting temperatures of a significant number of the sample compounds of the present invention are greater than 850° C. (Table 1). The isostructural compounds of the present invention include band gaps which are tunable. By "band gaps" it is meant that there is an energy difference between the highest occupied electron state and the lowest unoccupied electron state in theisostructural compounds. Further, by "tunable" it is meant that this energy difference can be manipulated to obtain the desired band gap. One way of tuning the band gaps of the isostructural compounds is by varying the values of the n and m (Table 1). For example, the band gap of KPbBiSe3 (n=1, m=1) was measured at ~0.60 eV which is in the desirable range for IR radiation detection. The compounds K2PbBi.sub.2S.sub.5 (n=2, m=1) and KPb2BiS.sub.4 (n=1, m=2) have optical bands gapsof 1.1 and 0.76 eV respectively. Depending on the values for n and m in AnM.sub.m M'nQ.sub.2n m a relatively wide range of band-gaps is possible, i.e., from about 0.05 eV to 1.55 eV. Band gap values for other representative isostructuralcompounds are given in Table 1. Infrared spectra showing the band-gap transition are shown in FIGS. 2A-C. For comparison purposes, the infrared spectrum for PbSe, which is commonly used as an IR detector and has an NaCl-type cubic crystal latticestructure, is shown in FIG. 2D. Another way of tuning the band gaps of the isostructural compounds of the present invention is by selecting certain cations and anions for A and Q, respectively. For example, if Se is chosen for Q and K is chosen for A, the isostructuralcompound KPb2BiSe.sub.4 has a band gap of 0.66 eV. If Q is changed from Se to Te, the corresponding compound KPb2BiTe.sub.4 has a band gap of less than 0.4 eV (Table 1). Depending on the application, appropriate band gaps can be chosen whichwould correspond to certain members of each family. One member of the family may be more appropriate for long wavelength detection, while another may be appropriate for short wavelength detection such as is used by IR lasers. Yet another way of controlling the band gaps for the overall composition is by combining various individual isostructural compounds of the present invention to form solid solutions of the type (Li, Na, K, Rb, Cs, Ag, TI)n(Sn, Pb, Ge, Ca, Sr,Ba)m(Bi, Sb)n(S, Se, Te)2n m. By "solid solutions" what is meant is a single, solid, homogenous crystalline phase containing two or more chemical species. A so-called solid solution would be made up of at least two distinct chemicalspecies such as AnPb.sub.mBi.sub.nSe.sub.2n m and AnPb.sub.mBi.sub.nTe.sub.2n m where Q represents two different anions (Sc and Te), or KnPb.sub.mBi.sub.nQ.sub.2n m and AgnPb.sub.mBi.sub.nQ.sub.2n m where A now represents twodifferent cations (K, Ag), by way of non-limiting example. Alternatively, M and M' may be represented by more than one element to form a solid solution. Examples of such compounds are, but not limited to, AgPbBi0.75Sb.sub.0.25Te.sub.3,AgPbBi0.5Sb.sub.0.5Te.sub.3, AgPbBi0.75Sb.sub.0.25Te.sub.3, AgPb0.75Sn.sub.0.25BiTe.sub.3, AgPb0.5Sn.sub.0.5BiTe.sub.3, and AgPb0.25Sn.sub.0.75BiTe.sub.3. Additional non-limiting examples of solid solutions are given in Table 1. It will be appreciated that although fractional numbers are used for the mole ratios, they can be combined to give the integer value for n or m. For example, in AgPb0.75Sn.sub.0.25BiTe.sub.3, Pb Sn represent M and their combined molefractions are equal to 1, the value for m. While the n and m values in the pure isostructural compounds provide a coarse dial to control band-gap, the solid solutions give a final dial for band gap engineering. For example, KPb2BiSe.sub.4 has a band gap of 0.66 eV whileKPb2BiTe.sub.4 has a band gap of less than 0.40 eV (Table 1). Therefore, solid solutions KPb2BiSe.sub.3Te, KPb2BiSe.sub.2Te.sub.2 and KPb2BiSeTe.sub.3 will all have band gaps that fall somewhere between 0.66 and 0.40 eV. Theformation of solid solutions with these compositions provides yet another means for tuning the band gap. The isostructural compounds of the present invention can be used in optical applications including, for example, infrared and near infrared detectors, lasers and photovoltaic cells such as solar cells by way of non-limiting example. In opticalapplications, at least two materials having different band gaps are layered together to give the desired optical properties. The isostructural compounds of the present invention have a wide range of band gaps that can be finely tuned to give optimalperformance in such optical applications. In addition, the lattice structures are identical, allowing for superior lattice matching of the layers compared to the layering of two compounds with varying structures. The isostructural compounds of the present invention can also be used in multi-spectral sensors. Multi-spectral sensors (e.g. long wavelength and short wavelength) offer the possibility of improved clutter rejection and improved recognitionrange. The proper fusing of the information from each spectral band is key to the realization of these advantages. One such application is the two color, stacked, co-located, three terminal back-to-back diodes pixel. Two color, simultaneousintegration HgCdTe back-to-back diodes staring IRFPAs have been produced. Love, P. et al., Proceedings of the IRIS Detectors Specialty Group Symposium, pp. 169-186 (1995). The materials of the present invention are well suited for this multispectralconfiguration because they provide lattice matching over a wide range of n and m. For example, a two-material stacked structure with KPb2BiSe4 (Eg=0.66 eV) and KPb8BiSe.sub.10 (Eg=0.35 eV) can be built either by vapor deposition techniques orby fusion bonding of two individual crystals as illustrated in FIG. 3 along with the respective lattice constants, a. Current approaches using HgCdTe solid solutions (comprising HgTe and CdTe) require the growth of heterojunctions, which then requiresprecise lattice matching. Current techniques result in a lattice mismatch as great as 4-6%, compromising the performance of the multispectral sensor. In contrast, the isostructural compounds of the present invention can be utilized as individualcompounds and therefore should not require precise compositional control at the junction. The lattice mismatch using the isostructural compounds of the present invention is significantly less than 4-6% and is <2% with KPb2BeSe.sub.4 andKPb8BiSe.sub.10 in a stacked structure (FIG. 3). Another application for isostructural compounds of the present invention is in thermoelectric devices. Such devices may be used for heating, cooling, temperature stabilization, power generation and temperature sensing. Recently, significantadvances in the synthesis and design of new systems such as in filled skutterudites and quantum well structures provided new hope that high performance thermoelectric materials may be attainable. While the efficiency of thermoelectric coolers operatingnear room temperature is only about 10% of Carnot efficiency, the thermodynamics of thermoelectric cooling suggests that achieving close to 100% of Carnot efficiency is possible employing the isostructural compounds of the present invention. Thermoelectric devices are essentially heat pumps and power generators which follow the laws of thermodynamics in the same manner as mechanical heat pumps, refrigerators, or any other apparatus used to transfer heat energy. The principaldifference is that thermoelectric devices function with solid state electrical components (thermocouples) as compared to more traditional mechanical/fluid heating and cooling components. An efficient thermoelectric device is fabricated from twomaterials, one N-type and the other a P-type conductor. Each material is separately chosen to optimize the figure of merit, zT, where zT=(S2ς/κ)T; S is the thermopower or Seebeck coefficient (μV/K), ς the electricalconductivity (S/cm), κ the thermal conductivity (W/m-K) and T the temperature (K). Therefore, to obtain a thermoelectric material having a high thermoelectric performance, it is desirable to select a material having a large Seebeck coefficient,S, a large electrical conductivity, ς, and a small thermal conductivity, κ. The isostructural compounds of the present invention have a high thermoelectric performance resulting from large Seebeck coefficients, large electrical conductivities and small thermal conductivities (Table 1). The Seebeck coefficients of thecompounds of the present invention range from about . -.30 μV/k to about . -.500 μV/k and the electrical conductivities from about 10 to about 7000 S/cm. FIG. 4 shows the effect of increasing temperature on the inverse of electrical conductivity (resistivity) while FIG. 5 shows the effect of increasing temperature on the Seebeck coefficient of the compound KPb8BiTe.sub.10. Increasing thetemperature results in a larger Seebeck coefficient. The isostructural compounds of the present invention may be doped with selected impurities to produce P-type and N-type conductors having improved thermoelectric properties such as enhanced Seebeck coefficients and figures of merit (zT). In anenhanced N-type conductor, one atom is replaced by another atom having more valence electrons, wherein the extra electrons are not needed for bonding and are free to move throughout the crystal. Alternatively, a P-type conductor is formed when an atomin the isostructural compound is replaced by another atom with fewer electrons, leaving a bond vacant wherein this shortage is referred to as a hole. The compounds of the present invention always exhibit P-type conductivity when the compounds are prepared by high temperature reaction with stoichiometric amounts of the constituent components. Enhanced P-type semiconductors can be produced fromthe compounds of the present invention. For the cationic sites of Bi or Sb (Group V) and Pb or Sn (Group IV), doping with one electron deficient elements such as Group IV elements (Ge, Sn, Pb) and Group III elements (Al, Ga, In, TI), respectively, mayproduce more hole carriers which give rise to improved electrical properties. The isostructural components of the present invention can be used to produce N-type semiconductor materials by doping with various impurities. Isovalent anionic dopants, where S or Se is substituted for Te and S for Se may be used in about lessthan 1 atomic percent. Other examples of compounds that can be used for doping are the metal halides SbX3, BiX3, and Hg2Cl.sub.2, DX2 where X is chlorine, bromine, iodine and mixtures thereof and D is chromium, manganese, iron,cobalt, nickel, copper, zinc, magnesium and mixtures thereof. These are examples of compounds that can be used for doping and are in no way meant to be limiting. It should be appreciated by those skilled in the art that any dopant can be used to dopethe isostructural compounds of the present invention to form enhanced P-type and N-type semiconductors. Doping of the isostructural compounds of the present invention can be achieved by introducing the desired amount of dopant during synthesis. Stoichiometric amounts of the dopant can be added to the starting materials. Alternately, the compoundsof the present invention can be doped by co-melting the desired compound and the dopant and recooling the new mixture. The amount of dopant preferably ranges from 0.0001% to 4% by weight. The isostructural compounds of the present invention may be used in a thermoelectrical conversion process in a thermoelectric conversion device. The thermoelectric conversion process using the isostructural compounds of the present invention maytake any appropriate form, such as any known device and/or structure, as long as thermoelectric conversion principles are met. Such devices may be, but are not limited to, electrical power generators, heater, coolers, thermocouples, temperature sensorsand radioisotope thermoelectric generators. Other thermoelectric devices that can be manufactured using the compounds of the present invention may be used in waste heat recovery systems, automobiles, remote power generators, temperature sensors andcoolers for advanced electronic components such as field effect transistors, as non-limiting examples. The isostructural compounds of the present invention may take any number of appropriate shapes. The compounds may be used in a lump shape or they may be formed in the shape of a thin film by a growth method, vapor deposition, or other techniquesknown to those skilled in the art. Regardless of the shape, the isostructural compounds of the present invention have excellent conductivity and thermoelectric properties. TABLE-US-00001 TABLE 1 Lattice Band Melting Parameter Gap Point κa ςb Sc Compound n m (Å) (eV) ° C.) (W/m-K) (S/cm) (μV/K) AgPbBiS3 1 1 5.753 0.54 >910 1.3 25 -160 AgPbBiSe3 1 1 5.955 0.48>920 1.0 67 -130 AgPbBiTe3 1 1 6.28 0.28 >900 1.15 300 -40 AgPbSbTe3 1 1 AgSnBiTe3 1 1 6.1639 AgPb2BiTe.sub.4 1 2 6.323 0.29 >850 1.2 180 -165 AgSn8BiSe.sub.10 1 8 5.926 >900 1.2 AgPb10BiS.sub.12 1 10 6.117 0.31>900 1.1 AgPb10BiTe.sub.12 1 10 6.452 0.29 >850 1.1 AgPb10SbTe.sub.12 1 10 6.441 0.29 >850 1.0 AgPb10BiSe.sub.12 1 10 6.118 AgSn10BiS.sub.12 1 10 6.259 6700 AgPb10SbS.sub.12 1 10 5.905 300 AgPb13BiTe.sub.15 1 136.44 0.23 >800 1.6 AgPbBiTe2Se 1 1 6.185 1.3 400 -58 AgPbBiTe2.25Se.sub.0.75 1 1 6.19 1.1 150 -40 AgPbBiTe2.5Se.sub.0.5 1 1 6.247 1.6 77 -80 AgPbBiTe2.75Se.sub.0.25 1 1 6.274 1.15 133 -105 AgPbBi0.1Sb.sub.0.9Te.sub.3 1 1AgPbBi0.05Sb.sub.0.95Te.sub.3 1 1 AgPbBi0.75Sb.sub.0.25Te.sub.3 1 1 6.261 0.268 29 -68 AgPbBi0.5Sb.sub.0.5Te.sub.3 1 1 6.261 0.27 3.91 250 AgPbBi0.25Sb.sub.0.75Te.sub.3 1 1 10 370 AgPb0.75Sn.sub.0.25BiTe.sub.3 1 1 0.18 59 -33AgPb0.5Sn.sub.0.5BiTe.sub.3 1 1 310 AgPb0.25Sn.sub.0.75BiTe.sub.3 1 1 685 35 AgPbBiTe1.5Se.sub.1.5 1 1 6.13 AgPbBiTeSe2 1 1 6.078 AgPbBiTe0.5Se.sub.2.5 1 1 6.036 AgPbBiTe2.95Se.sub.0.05 1 1 6.223 -64AgPbBiTe2.75Se.sub.0.25 1 1 6.245 666 -60 AgPbSb0.95Bi.sub.0.05Te.sub.3 1 1 0.37 430 KPb3BiS.sub.5 1 3 5.949 0.71 >850 K5Pb.sub.16Bi.sub.5S.sub.26 5 16 5.947 0.69 >850 KPb7BiS.sub.9 1 7 5.937 0.63 >850KPb9BiS.sub.11 1 9 5.947 0.53 >850 K7PbBi.sub.7S.sub.15 7 1 5.975 1.02 >850 K8PbBi.sub.8S.sub.17 8 1 6.006 1.24 >850 K11PbBi.sub.11S.sub.23 1 1 6.009 1.30 >850 KPbBiSe3 1 1 6.182 0.6 1004 KPb2BiSe.sub.4 1 26.185 0.66 958 -515 KPb3BiSe.sub.5 1 3 6.175 0.64 977 40 KPb4BiSe.sub.6 1 4 6.154 0.56 1015 210 KPb5BiSe.sub.7 1 5 6.142 0.45 1035 500 KPb10BiSe.sub.12 1 10 6.112 0.32 >850 K2Pb.sub.23Bi.sub.2Se.sub.27 2 23 6.111 >850K2PbBi.sub.2Se.sub.5 2 1 6.007 0.62 >900 K3PbBi.sub.3Se.sub.7 3 1 6.196 0.67 >900 KPbBiTe3 1 1 0.45 >900 <1.5 -125 KPb2BiTe.sub.4 1 2 6.469 <0.40 >900 1.7 700 -115 KPb3BiTe.sub.5 1 3 6.467 <0.38 >900 1.5800 KPb4BiTe.sub.6 1 4 6.479 <0.37 >900 1.7 1000 -155 KPb8BiTe.sub.10 1 8 6.458 <0.36 >900 2.1 1100 -150 KPb10BiTe.sub.12 1 10 6.472 <0.36 >900 2.2 960 -145 KPb10BiSeS.sub.11 1 10 5.9815 KPb10BiSe.sub.3S.sub.9 110 6.0199 KPb10BiSe.sub.6S.sub.6 1 10 6.0635 KPb10BiSe.sub.9S.sub.3 1 10 6.1055 KPb10BiSe.sub.11S 1 10 6.1336 KPb10Bi.sub.0.75Sb.sub.0.25Te.sub.6Se.sub.6 1 10 6.3284 935 990 KPb10Bi.sub.0.5Sb.sub.0.5Te.sub.6Se.sub.6 1 10 6.3073935 595 KPb10Bi.sub.0.75Sb.sub.0.25Te.sub.6Se.sub.6 1 10 6.2846 935 380 KPb8Sn.sub.2BiTe.sub.6Se.sub.6 1 10 6.2949 860 450 KPb6Sn.sub.4BiTe.sub.6Se.sub.6 1 10 6.27 860 40 KPb4Sn.sub.6BiTe.sub.6Se.sub.6 1 10 6.2544 860 100KPb2Sn.sub.8BiTe.sub.6Se.sub.6 1 10 6.2094 860 360 KPbSbTe3 1 1 KPb5SbTe.sub.7 1 5 6.448 13 KPb10SbTe.sub.7 1 5 6.459 215 KSnBiTe3 1 1 150 KSn5BiTe.sub.7 1 5 230 KSn10BiTe.sub.12 1 10 6.292 990 KSnSbTe3 1 1 210KSn5SbTe.sub.7 1 5 6.278 2630 KSn10SbTe.sub.12 1 10 6.363 4250 Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and the scope to the invention. * * * * * Other References
Field of SearchSELENIUM OR TELLURIUM OR COMPOUND THEREOFSULFUR OR COMPOUND THEREOF Sulfur, selenium, or tellurium containing Semiconducting type Particular detection structure (e.g., MOS, PIN) Of material other than germanium, diamond, or silicon Light Temperature Group III-V compound (e.g., InP) Group II-VI compound (e.g., CdTe, Hg x Cd 1-x Te) Chalcogenide containing (S, O, Te, Se) Group IV element containing (C, Si, Ti, Ge, Zr, Sn, Hf, Pb) Group V metal containing (V, As, Nb, Sb, Ta, Bi) With concentrator, housing, cooling means, or encapsulated Silicon or germanium containing Selenium or tellurium containing Copper, lead, or zinc containing |
| ||||||||||||||
