Ge Content Research Articles

Middle range order and elastic properties of non-stoichiometric chalcogenide glasses in the AsS3 - GeS4 system

Longitudinal elastic modulus of glasses (GeS4)x (AsS3)1-x has been determined from experimentally measured density and ultrasound velocity with respect to the “first sharp diffraction peak (FSDP)” of the XRD halos, ascribed to intermediate range ordering. Quantitative analysis of FSDP allowed estimation of the size of correlated middle range ordered domains and inter domain distances dependent on glass composition. It was revealed that interdomain distance and average domains size are strongly correlated, both reaching the minimal value at composition that comprises 7,7 at.% Ge, therefore the domain concentration of this composition appears to be maximal. It was not found an apparent correlation between density or ultrasound velocity and middle range ordering parameters of the glass. However, a clearly visible correlation was found between Young’ modulus and concentration of structural domains: Young’ modulus linearly increases with domain concentration, with an exception of an only case occurring at low Ge concentration (∼x223C 4 at.%). The results are explained in terms of deep structural transformation in the middle range order caused by molecular reorganization, which controls the physical properties, including the elastic ones of the glass. The study has pointed out the light glasses of the AsS3-GeS4 system possessing enhanced elastic and sound characteristics available for application.

The effect of Si and Ge on the elastic properties and plastic deformation modes in high- and medium-entropy alloys

We employ quantum mechanics modeling to investigate the effects of Ge and Si solute elements on the elastic properties and plastic deformation modes in two families of high-entropy alloys, CoCrFeMnNi and CoCrFeNi, and medium-entropy alloy, CoCrNi. The static lattice constants and single-crystal elastic parameters are calculated for these three face-centered-cubic random solid solutions as a function of composition. Using the elastic constants, we analyzed mechanical stability, derived polycrystalline modulus, and evaluated solid-solution strengthening for these multi-component alloys. We fabricated (CoCrFeNi)100−x Six (x = 0, 4, 6) and measured the polycrystalline modulus and hardness. The calculated trends for Young's and shear modulus as well as lattice parameters were verified by our measurements. The dependence of generalized stacking fault energy on Ge and Si was studied in detail for the considered multi-component alloys. The competition between various plastic deformation modes was revealed based on effective energy barriers. Our calculations predict that the activated deformation modes in all the alloys studied here are the stacking fault mode (dominant) and the full-slip mode (secondary), and as the concentrations of Ge and Si increase, twining becomes favored.

Effect of Strain on the Epitaxy of B-Doped Si0.5Ge0.5 Source/Drain Layers

The impact of strain on the growth of in situ boron doped Si0.5Ge0.5 epitaxial layers is discussed. The lattice strain has been varied by changing the Si0.5Ge0.5 thickness and by growing the epitaxial layer on strain relaxed substrates with different Ge concentrations. With decreasing compressive strain, the B incorporation reduces, and the Ge concentration increases. Through density functional theory calculations, the dependence on the applied strain of the energetic cost for boron incorporation into the Si0.5Ge0.5 surface was investigated.

A Novel Approach for the Determination of the Ge Isotope Ratio Using Liquid-Liquid Extraction and Hydride Generation by Multicollector Inductively Coupled Plasma Mass Spectrometry.

In this work, a method for the accurate and precise determination of the Ge isotope ratio in synthetic water and natural samples of geological origin using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) with hydride generation was developed. The method was based on the liquid–liquid extraction of Ge to eliminate all elements affecting the generation of germanium hydrides. The standard-sample bracketing method was used to correct instrumental bias. Registration of analytical signal in time-resolved mode gave way to choose signals with best parameters and improved the precision of the results. Controlling the pH by using acetic buffer boosted the sensitivity by nearly five times in comparison to hydride generation methods suggested by other authors. The newly developed method is much simpler and quicker, does not need laborious Ge separation with ion-exchange resins, and thanks to its superior sensitivity, allows measurements of the Ge isotopic ratio in materials with relatively low Ge content. Delta values of the 74Ge/70Ge isotope ratio were measured in standard reference materials for which reference values were available in the GeoREM database. We demonstrated that the accuracy and precession of this method are equally good or better than methods proposed by other authors.

Theoretical study on the formation of diamond germanium vacancy color center

Germanium-vacancy (GeV) color centers in diamond are superior to other color centers in terms of luminescence intensity. The Ge-doping process is key to the successful preparation of GeV color centers in diamond. In this study, the formation mechanism of GeV color centers is explored via first-principles calculations of the adsorption and migration of Ge on the (001) surface of diamond. The results reveal that Ge atoms on the surface of completely hydrogenated diamond have a negative adsorption energy, indicating that they cannot be adsorbed. In contrast, the adsorption energy of Ge atoms on the surface of non-perhydrogenated diamond is relatively large, which indicates that the surface of non-perhydrogenated diamond can adsorb Ge atoms. When Ge atoms are closer to hydrogen defects, their adsorption energy is greater. As the extent of hydrogen deficiency increases, the overall adsorption energy increases accordingly. The hydrogen deficiency of the diamond surface may determine the extent of the Ge content on the diamond surface. Magnetic moment, differential charge, and Bader analyses reveal that charge is transferred between Ge and carbon atoms on the diamond surface. In addition, the Ge and carbon atoms form covalent bonds at positions where the adsorption energy is maximum. Finally, the migration of Ge atoms on the diamond surface enables them to reach a stable position easily.

Pressure-Tunable Crystal Structure and Magnetic Transition Temperature of the Nowotny Chimney-Ladder CrGeγ Phase.

A Nowotny chimney-ladder (NCL) chromium germanide (CrGeγ) with varying compositions has been synthesized under high pressure. Crystal structure parameters of the NCL CrGeγ have been calculated by Le Bail refinement based on the superspace group. The refined γ of CrGeγ increases with the synthesis pressure, indicating an increasing Ge content. The NCL CrGeγ phases are ferromagnetic at T = 2 K regardless of their composition, and the magnetic transition temperature (TC) increases when the γ becomes higher. It is noteworthy that CrGe1.763 and CrGe1.774 synthesized at P = 10 and 14 GPa have magnetic transition temperatures of T = 295 and 333 K above room temperature, respectively. Surprisingly, the magnetic transition temperature has changed by ΔTC = 270 K, although the γ values of the raw material and the sample synthesized at P = 14 GPa differ by only Δγ = 0.05, corresponding to an atomic concentration of 0.62 atom %. The synthesis pressure acts as an essential parameter in tuning the composition of the NCL phase. Accordingly, the high-pressure synthesis may significantly control several physical characteristics of NCL phases by utilizing compositional and structural modulation.

Enhancement of concentration of XeV and GeV centers in microcrystalline diamond films through He+ irradiation

Atomic defect centers in diamond have been widely exploited in numerous quantum applications like quantum information, sensing, quantum photonics and so on. In this context, there is always a requirement to improve and optimize the preparation procedure to generate the defect centers in controlled fashion, and to explore new defect centers which can have the potential to overcome the current technological challenges. Through this work we report enhancing the concentration of Ge and Xe vacancy centers in microcrystalline diamond (MCD) by means of He+ irradiation. We have demonstrated controlled growth of MCD by chemical vapor deposition (CVD) and implantation of Ge and Xe ions into the CVD-grown samples. MCDs were irradiated with He+ ions and characterized through optical spectroscopy measurements. Recorded photoluminescence results revealed a clear signature of enhancement of the Xe-related and Ge vacancies in MCDs.

A dislocation-driven laminated relaxation process in Si1−xGex grown on Si (001) by molecular beam epitaxy

Based on the successful epitaxial growth of Si1−xGex with a full spectrum of Ge content, we have grown a series of high-quality Si0.4Ge0.6 films with different thicknesses on Si (001) substrates using molecular beam epitaxy. A laminated relaxation process is observed in the Si1−xGex samples above a certain thickness. Strain analyses by X-ray diffraction and high-resolution transmission electron microscopy have shown that the highly strained pseudomorphic layer can be preserved even after the relaxation has occurred. We propose a dislocation-driven relaxation mechanism and attribute this anomalous relaxation phenomenon to the low growth temperature used. This study shows that the manipulation of dislocation can be an effective way to enhance the growth of a highly mismatched heterostructure system.

Metallographic Cooling Rate and Petrogenesis of the Recently Found Huoyanshan Iron Meteorite Shower

AbstractThe Huoyanshan iron meteorite shower, recently found in the Gobi Desert of Hami, Xinjiang, China, has very high Ni (21.1 wt%) content and low Au (2.0 ppm), Ir (0.02 ppm), Ge (1.7 ppm), and Ga (1.1 ppm) contents, and was classified into IAB‐sLH subgroup. The iron has a finest octahedrite structure of Widmanstätten pattern (the intergrowth of kamacite [α] and taenite [γ]) with plessite matrix, and euhedral schreibersite (Sch) crystals exclusively enclosed in kamacite bands. The textural features suggest the following formation process: γ→γ + Sch→γ + Sch + α, and then γ→α2 + γ. The metallographic cooling rate of Huoyanshan iron was determined to be 3–50°C/Myr using both the taenite Ni profile‐matching and taenite central Ni content methods, with the bandwidths corrected for crystallographic orientation by electron backscatter diffraction (EBSD). The cooling rate of Huoyanshan is consistent with other sLH irons and confirms the slow cooling history of the IAB low‐Au subgroups. These slow cooling rates require immediate re‐accretion with a thick brecciated fragments layer in the parent body after the impact melting event. The depleted but unfractionated Re, Os, Ir, Ru, and Pt and the enriched Pd and Au abundances of Huoyanshan iron and other sLH subgroup irons show complementary feature to that of refractory metal nuggets in Ca‐, Al‐rich inclusions (CAIs), which could be explained by extracting the metallic Fe‐Ni with HSE predominantly remained in CAIs from a CAI‐bearing asteroid. The very high Ni content of sLH subgroup and its Mo isotope evidence (Worsham et al., 2017, https://doi.org/10.1016/j.epsl.2017.02.044) suggest it has an oxidized parent body with non‐carbonaceous chondrite‐like precursor composition. We propose that the sLH subgroup was produced by impact melting of a LL like and CAI‐bearing asteroid, followed by fast burying of thick and porous silicate breccia.

Ge doping of β-Ga2O3 by MOCVD

We report on the Ge doping of Ga2O3 using metalorganic chemical vapor deposition (MOCVD) epitaxy. The effects of the GeH4/N2 flow rate, substrate temperature, VI/III ratio, type of Ga precursor, and MOCVD reactor geometry on the incorporation efficiency of Ge into Ga2O3 were explored. The Ge concentration incorporated into the films was quantified using Hall and secondary ion mass spectroscopy measurements. The increase in the GeH4/N2 flow rate, decrease in the substrate temperature, and increase in the VI/III ratio increase the amount of Ge incorporated into Ga2O3. The incorporation of Ge into the lattice of Ga2O3 was found to be strongly dependent on the substrate temperature, i.e., lowering the growth temperature leads to a higher doping concentration. Films with a free carrier concentration ranging from ∼2 × 1016 to ∼3 × 1020 cm−3 and corresponding mobilities ranging from ∼140 to ∼38 cm2/Vs were realized. The incorporation of Ge into the films was also found to be strongly dependent on the metalorganic precursor type used for the growth of the Ga2O3 film. We found that it was more challenging to dope Ga2O3 with Ge using trimethylgallium rather than triethylgallium as a source for Ga. Additionally, we found that Ge doping has a strong memory effect dependent on the reactor geometry. The result highlights the challenges in achieving controllable Ge doping for n-type conductivity despite all the positive indicators from theoretical studies that suggest that Ge is a suitable dopant candidate for Ga2O3 similar to Si and Sn.

Evolution of a hydrothermal ore-forming system recorded by sulfide mineral chemistry: a case study from the Plaka Pb\u2013Zn\u2013Ag Deposit, Lavrion, Greece

Laser ablation-inductively coupled plasma-mass spectrometry and electron-probe microanalysis were used to investigate the trace-element contents of sphalerite, chalcopyrite and pyrite from the Plaka Pb–Zn–Ag deposit. Using petrographic observations, the analytical results could be linked to the temporal evolution of the Plaka ore-forming system. Sphalerite chemistry reliably records the temperature and fS2 evolution of the system, with estimated formation temperatures reproducing the microthermometric results from previous fluid-inclusion studies. Chalcopyrite chemistry also shows systematic variations over time, particularly for Cd, Co, Ge, In, Sn and Zn concentrations. Measurable pyrite was only found in association with early high-temperature mineralisation, and no clear trends could therefore be identified. We note, however, that As and Se contents in pyrite are consistent with formation temperatures estimated from co-existing sphalerite. Statistical analysis of the sphalerite data allowed us to identify the dominant geological controls on its trace-element content. The three investigated factors temperature, fS2, and sample location account for > 80% of the observed variance in Mn, Fe, Co, Ga, Ge, In, Sb and Hg concentrations, and > 60% of the observed variance in Cd and Sn concentrations. Only for Cu and Ag concentrations is the explained variance < 50%. A similarly detailed analysis was not possible for chalcopyrite and pyrite. Nevertheless, comparison of the results for all three investigated minerals indicates that there are some systematic variations across the deposit which may be explained by local differences in fluid composition.

Quartz chemistry of granitic pegmatites: Implications for classification, genesis and exploration

Quartz from 254 pegmatites representing eight pegmatite fields and provinces worldwide was investigated by laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to determine concentrations of trace elements Al, Ti, Li, Ge, B, Be, Rb, Na, K, Ca, P, Ga, Sb, Zn and U. A total of 271 new analyses combined with 535 published LA-ICP-MS quartz chemistry data were evaluated with binary and ternary trace element discrimination plots and principal component analysis (PCA). The classifications applied for discrimination of pegmatite types include the widely applied NYF(Nb-Y-F) - LCT(Li-Cs-Ta) classification and the new RMG (pegmatites derived from residual melts of granite magmatism) - DPA (pegmatites as direct products of anatexis) grouping. Pegmatites of both classifications can be well distinguished via Al-Ti, Al-Li and Al/Ti-Ge/Ti binary trace element plots and the Ti - Al/10 - 10*Ge ternary diagram. PCA applied to Al, Li, Ti, Be, B, Ge and Rb contents in quartz allowed to further distinguish between anatectic DPA-1 (Li-enriched DPA) and granite-pluton-derived RMG-1 (Li-enriched RMG) pegmatites. Some pegmatite fields and provinces (Hagendorf-Pleystein, Oxford County) are distinguishable by region-specific Li, Ge and Al contents. The results imply that the chemistry of pegmatite quartz is mainly controlled by the origin (source rock chemistry) of pegmatite melts and, to a much lesser extent, by the geodynamic setting of the pegmatite fields and provinces. Chemically primitive NYF and DPA-2 type pegmatites contain quartz with the lowest total trace-element contents and lowest internal-pegmatite trace-element variation, making it potentially suitable for high-tech application. Pegmatite quartz containing >30 μgg-1 Li and >100 μgg-1 Al is strongly indicative of economic spodumene/montebrasite mineralization and, thus, serves as a strong Li-mineralization pathfinder mineral. Quartz with >5 μgg-1 B may be a potential indicator for gem-quality tourmaline mineralization.

Germanium Nanocrystal Properties from Photoluminescence

Morphological information has been obtained using the strong near-infrared photoluminescence emitted by germanium (Ge) nanocrystals (NCs) coherently imbedded in SiGe alloy layers, grown by molecular beam epitaxy on Si substrates. The emission spectra are analyzed for the effects of strain, carrier confinement, and disorder over a wide range of Ge concentrations in the surrounding SiGe medium. This analysis provided significant insight into the properties of the Ge nanocrystals, including their size and shape. We also discuss the mechanisms leading to the high quantum efficiency observed for emission from the Ge nanocrystals at low temperatures. We indicate how direct gap behavior might be achieved for Ge NCs lattice matched within dilute Ge1-ySny alloys, where tensile strain would be present in the NCs in all three directions.

Redistribution and transformation mechanisms of gallium and germanium during coal combustion

Gallium (Ga) and germanium (Ge) are strategically critical rare elements (CREs) which are of growing significance for the rising demand of emerging energy-efficient technologies and high-tech applications. With the increasing demand and exhaustion of conventional ores of these CREs, extraction of CREs from metalliferous coal may be a viable approach to providing stable alternative sources. Understanding of the transformation behavior and associations of CREs during combustion processes are of significance for the design of recovery applications. The Ga/Ge coal from Mangniuhai Coalfield was collected to determine the redistribution and transformation behavior of CREs during combustion at 1000 °C. The effect of ash components on the redistributions of Ga and Ge during combustion was determined via both experimental laboratory simulations and thermodynamic equilibrium calculations. The experiments were performed in a fluidized bed reactor in combustion temperature range of 500–1000 °C. Sequential chemical extraction was conducted to determine the transformation characterizations of associations of Ga and Ge during combustion. The concentrations of Ga and Ge in combustion residues are reached to the cut-off grades suggest that these CREs deserve further utilization. Ga and Ge are mainly enriched in fly ash (>60%) when compared to that of bottom ash. The redistribution characterizations of Ga and Ge during combustion with ash components are determined by combustion temperature, ash component type and adding amount. Ga and Ge can be redistributed to ash phases more effectively by adding Si, Al, Na and K -based additives during the combustion. Ga and Ge are retained in ash phases as a result of the formation of non-volatilized steady species arising from interactions with the ash components. Si, Al, Na and K based compounds are regarded as the appreciable additives for the excellent capture potential of gaseous CREs during high temperature combustion. The results may provide useful information for the development of CREs enrichment, extraction and separation technologies from coal.

Secondary metabolites released by the rhizosphere bacteria Arthrobacter oxydans and Kocuria rosea enhance plant availability and soil–plant transfer of germanium (Ge) and rare earth elements (REEs)

Here, we explore effects of metallophore-producing rhizobacteria on the plant availability of germanium (Ge) and rare earth elements (REEs). Five isolates of the four species Rhodococcus erythropolis, Arthrobacter oxydans, Kocuria rosea and Chryseobacterium koreense were characterized regarding their production of element-chelators using genome-mining, LC-MS/MS analysis and solid CAS-assay. Additionally, a soil elution experiment was conducted in order to identify isolates that increase solubility of Ge and REEs in soil solution. A. oxydans ATW2 and K. rosea ATW4 released desferrioxamine-, bacillibactin- and surfactin-like compounds that mobilized Ge and REEs as well as P, Fe, Si and Ca in soil. Subsequently, oat, rapeseed and reed canary grass were cultivated on soil and sand and treated with cells and iron depleted culture supernatants of A. oxydans ATW2 and K. rosea ATW4. Inoculation increased plant yield and shoot phosphorus (P), manganese (Mn), Ge and REE concentrations. However, effects of the inoculation varied substantially between the growth substrates and plant species. On sand, A. oxydans ATW2 increased accumulation of REEs in all plant species and root–shoot translocation in rapeseed, while K. rosea ATW4 enhanced REE accumulation in rapeseed only, without effects on other plant species. Sand-cultured oat plants showed increased Ge accumulation and root–shoot translocation in presence of A. oxydans ATW2 cells and K. rosea ATW4 supernatant; however, there was no effect on other plant species, irrespective the growth substrate used. In contrast, soil-cultured rapeseed showed enhanced REE accumulation in presence of cells of A. oxydans ATW2 while there were no effects on other plant species and Ge. The processes involved are not yet fully understood. Nevertheless, we demonstrated that chemical microbe–soil–plant relationships influence plant availability of nutrients together with Ge and REEs, which has major implications on our understanding of biogeochemical element cycling and development of sustainable bioremediation and biomining technologies.

Impacts of Equivalent Oxide Thickness Scaling of TiN/Y₂O₃ Gate Stacks With Trimethylaluminum Treatment on SiGe MOS Interface Properties

Ultrathin equivalent oxide thickness (EOT) scaling of TiN/Y2O3 /SiGe gate stacks using a trimethylaluminum (TMA) treatment was studied. In comparison to previously reported high-k/SiGe MOS interfaces utilizing various Ge contents, we obtained an EOT scaling down to 1 nm with ultralow interface trap densities ( $\text{D}_{\text {it}}$ ). In addition, the impact of EOT scaling on the SiGe MOS interface properties has been investigated. We found the stress-induced degradation at the SiGe interface from constant gate biasing can be suppressed by scaling the thickness of Y2O3.

Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals

We present a detailed study regarding the bandgap dependence on diameter and composition of spherical Ge-rich GexSi1−x nanocrystals (NCs). For this, we conducted a series of atomistic density functional theory (DFT) calculations on H-passivated NCs of Ge-rich GeSi random alloys, with Ge atomic concentration varied from 50 to 100% and diameters ranging from 1 to 4 nm. As a result of the dominant confinement effect in the DFT computations, a composition invariance of the line shape of the bandgap diameter dependence was found for the entire computation range, the curves being shifted for different Ge concentrations by ΔE(eV) = 0.651(1 − x). The shape of the dependence of NCs bandgap on the diameter is well described by a power function 4.58/d1.25 for 2–4 nm diameter range, while for smaller diameters, there is a tendency to limit the bandgap to a finite value. By H-passivation of the NC surface, the effect of surface states near the band edges is excluded aiming to accurately determine the NC bandgap. The number of H atoms necessary to fully passivate the spherical GexSi1−x NC surface reaches the total number atoms of the Ge + Si core for smallest NCs and still remains about 25% from total number of atoms for bigger NC diameters of 4 nm. The findings are in line with existing theoretical and experimental published data on pure Ge NCs and allow the evaluation of the GeSi NCs behavior required by desired optical sensor applications for which there is a lack of DFT simulation data in literature.

Protection of silver electrodeposit surfaces against accelerated and natural atmospheric corrosion by Ge incorporation in Ag structure; a microstructural investigation

Silver, as the most reactive noble metal, tarnishes immediately after exposure to industrial atmosphere or indoor S-bearing air. In this study, tarnish resisting and long term microstructural stability of silver-germanium (Ag-Ge) coating in industrial atmosphere is investigated and compared to silver electrodeposits. Ag-Ge coatings were electrodeposited on copper from cyanide base bath by DC current application. Coatings consisting about 0.5 to 6wt.% Ge have been studied and the optimum content of Ge in the coating was found to be 6 wt.% regarding dense and uniform microstructure along with best tarnish resistance and long term microstructural stability that has been discussed in this work. Ge forms a thin protective oxide layer, so a small incorporation of Ge in Ag structure, could improve tarnish resistance to a large extent. Tarnish resistance of samples have been evaluated according to ISO 4538 standard and considering color and reflectivity change detected by UV-Visible spectrometer. In addition, X-ray Diffraction (XRD) results were used to determine the crystalline structure of coatings before and after tarnish resistance and atmospheric corrosion. XRD patterns in grazing mode indicated the formation of Ge-Oxide passive layer on the Ag-6Ge surface which is known as the key factor for this sample's best performance. Scanning Electron Microscopy (SEM) along with Field Emission Scanning Electron Microscopy (FESEM) equipped with Energy Dispersive Spectrometry (EDS) were used for microscopic analysis and surface characterization of samples. The various tarnish behavior of the coatings were evaluated and discussed via correlation to their microstructural characteristics in both severe and low aggressive conditions.

Pulsed laser melting of implant amorphized Si1-xGex thin films

Nanosecond pulsed laser annealing using a frequency doubled Nd:YAG laser (λ = 532 nm) was performed on undoped implant amorphized Si and 40 nm Si1-xGex epitaxial thin films ranging from x = 0.1 to 0.5. Ge+ implants were used to create ~ 15 nm thick surface amorphous layers. The microstructural evolution of the layers was investigated for laser powers that ranged from the sub-melt, partial amorphous layer melt, full amorphous layer melt, to full epi-layer melt regimes. Time resolved reflectometry and transmission electron microscopy was used to couple the impact of melt dynamics with resulting microstructures and to determine processing benchmarks as a function of Ge concentration. It was shown that for the right combination of power and amorphous layer thickness, defect free regrowth is possible. At melt depths ≥ 22 nm for the Si0.7Ge0.3 films, it was found that progressive liquid/solid interface roughening during solidification led to lateral germanium segregation coupled with the formation of dislocation half loops and dislocation loop clusters at the surface. These results are important for the exploration of pulsed laser melting of Si1-xGex for CMOS source/drain contact and channel strain engineering applications.

Effects of Ge Doping on the Charge Transport and Thermoelectric Properties of Permingeatites Cu3Sb1−yGeySe4

Permingeatites Cu3Sb1−yGeySe4 (0 ≤ y ≤ 0.14) were synthesized by mechanical alloying and hot pressing. The charge-transport parameters (Hall coefficient, carrier concentration, mobility, and Lorenz number) and thermoelectric properties (electrical conductivity, Seebeck coefficient, power factor, thermal conductivity, and figure of merit) were examined with respect to the Ge doping level. A single permingeatite phase with a tetragonal structure was obtained without subsequent heat treatment, but a small amount of the secondary phase Cu2GeSe3 was found for the specimens with y ≥ 0.08. All hot-pressed compacts exhibited a relative density of 97.5%–98.3%. The lattice constants of the a-axis and c-axis were decreased by the substitution of Ge at the Sb sites. As the Ge content increased, the carrier concentration increased from 5.2 × 10&lt;sup&gt;18&lt;/sup&gt; to 1.1 × 10&lt;sup&gt;20&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt;, but the mobility decreased from 92 to 25 cm&lt;sup&gt;2&lt;/sup&gt;·V&lt;sup&gt;−1&lt;/sup&gt;·s&lt;sup&gt;−1&lt;/sup&gt;. The Lorenz number of the undoped Cu3SbSe4 implied a non-degenerate semiconductor behavior, ranging from (1.57–1.56) × 10&lt;sup&gt;−8&lt;/sup&gt; V&lt;sup&gt;2&lt;/sup&gt;·K&lt;sup&gt;−2&lt;/sup&gt; at 323–623 K. The thermoelectric figure of merit was 0.39 at 623 K, resulting from a power factor of 0.49 mW·m&lt;sup&gt;−1&lt;/sup&gt;·K&lt;sup&gt;−2&lt;/sup&gt; and a thermal conductivity of 0.76 W·m&lt;sup&gt;−1&lt;/sup&gt;·K&lt;sup&gt;−1&lt;/sup&gt;. However, the Lorenz numbers of the Gedoped specimens indicated degenerate semiconductor characteristics, increasing to (1.63–1.94) × 10&lt;sup&gt;−8&lt;/sup&gt; V&lt;sup&gt;2&lt;/sup&gt;·K&lt;sup&gt;−2&lt;/sup&gt; at 323–623 K. The highest thermoelectric figure of merit of 0.65 was at 623 K for Cu3Sb0.86Ge0.14Se4, resulting from the significantly improved power factor of 0.93 mW·m&lt;sup&gt;−1&lt;/sup&gt;·K&lt;sup&gt;−2&lt;/sup&gt; and the thermal conductivity of 0.89W·m&lt;sup&gt;−1&lt;/sup&gt;·K&lt;sup&gt;−1&lt;/sup&gt;. As a result, the thermoelectric properties were remarkably enhanced by doping Ge into the Sb sites of the permingeatite.