Ge Doping Research Articles

Exploiting synergies for high thermoelectric performance in higher manganese silicide-based semiconductors through element Co-doping, energy filtering, and phonon scattering

Higher manganese silicide (HMS) is a promising thermoelectric (TE) semiconductor that operates effectively at medium temperatures. It is characterized by its abundance, environmental friendliness, and desirable impact resistance properties. To enhance the TE properties of HMS, this study employs isoelectronic anion and cation codoping, combined with embedded quantum dot (QD) techniques. The introduction of element doping and nanoinclusions, such as Mn0.96Re0.04(Si0.96Ge0.04)1.79+1.5%Ag2Pt QDs sample, leads to an approximately 85% increase in electrical conductivity. This boost is attributed to the adjustment of the band structure through Re, Ge, and Ag element doping and the charge transfer facilitated by MnSi, Si, and Pt precipitates. Furthermore, the enhanced PF of 1.85 × 10−3 W m−1 K−2 at 773 K is approximately 29% higher than that of pure HMS. Simultaneously, the increase in point defects hampers the improvement of lattice thermal conductivity (κl) by intensively scattering short-wave phonons. This effect is complemented by the precipitation of Si, MnSi, Ag, and Pt nanoparticles, which increases the density of grain boundaries, enhances medium-wave phonon scattering, and substantially reduces κl to 1.45 W m–l K−1 (at 773 K), ∼30% lower than that of pure HMS. The figure of merit of the sample containing 1.5%Ag2Pt QDs at 823 K attains a value of 0.69, which is ∼52% and ∼19% higher than that of pure HMS and Re-Ge-double-doped samples, respectively. The incorporation of isoelectronic codoping, along with the integration of metastable QDs, is demonstrated as an effective strategy for enhancing TE properties.

Regulating SnZn defects and optimizing bandgap in the Cu2ZnSn(S,Se)4 absorption layer by Ge gradient doping for efficient kesterite solar cells

In recent years, the primary reasons for low efficiency Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have been attributed to SnZn defects and related defect clusters, as well as the balance of absorption layer bandgap for short-circuit current density (Jsc) and open-circuit voltage (Voc). Ge gradient has been theoretically proven to be an effective strategy to change traditional flat bandgap structure and suppress SnZn defects and related defect clusters for improving the device performance of CZTSSe solar cells. However, the potential of Ge gradient has not been fully verified. In this work, Ge doping effectively reduces the formation of SnZn defects and [2CuZn + SnZn] defect clusters in the CZTSSe absorption layer. In addition, it can be found that the construction of the V-type bandgap is the best solution for balancing between Voc and Jsc. By using the bandgap grading strategy, the disparity between the recombination barrier of the junction and the optical bandgap's minimum value is widened, thereby obtaining a large Voc. The V-type doped device has the highest efficiency when Voc is 0.45 V, which can reach 8.03%. This Ge graded substitution method provides an alternative absorption layer structure for improving Voc and the preparation of future high-efficiency kesterite photovoltaic devices.

Tailored absorption/emission and ultrastrong coupling from heavily doped germanium plasmonic antennas

We evaluate the performance of heavily doped germanium (Ge) on silicon as a mid-infrared plasmonic material using experimental data and benchmark it against noble metals such as Au. Thanks to the strong confinement provided by the high refractive index of the spacer layer (undoped Ge) in our material system, along with the tunable plasma frequency and low scattering rate of heavily doped Ge, we demonstrate an ultrastrong coupling regime between the localized surface plasmon (LSP) resonance and the optical modes associated with the Fabry-Perot resonance in metal-dielectric-metal (MDM) cylindrical periodic arrayed antennas. These MDM antennas made up of heavily doped Ge exhibit multispectral perfect absorption. The spectral profile and absorption intensity of the resonances can be controlled by altering the lateral and vertical device geometry of the MDM antennas. The anti-crossing behavior implying ultrastrong coupling is investigated. A Rabi splitting energy (of 451 cm−1 in unit of wavenumber) is achieved in the cylindrical periodic arrayed antennas, which is ∼20 % larger than that in 1D gratings reported in a recently published work [42]. As a key application, the MDM antennas provide tailored emission spectrum. Based on the heavily doped Ge material platform, we demonstrate a wavelength-adjustable, Si-CMOS compatible plasmonic architecture, with potential for enhanced mid-infrared radiation.

Improvement of PbSn Solder Reliability with Ge Microalloying-Induced Optimization of Intermetallic Compounds Growth.

PbSn solders are used in semiconductor devices for aerospace or military purposes with high levels of reliability requirements. Microalloying has been widely adopted to improve the reliability for Pb-free solders, but its application in PbSn solders is scarce. In this article, the optimization of PbSn solder reliability with Ge microalloying was investigated using both experimental and calculation methods. Intermetallic compounds (IMC) growth and morphologies evolution during reliability tests were considered to be the main factors of device failure. Through first-principle calculation, the growth mechanism of interfacial Ni3Sn4 was discussed, including the formation of vacancies, the Ni-vacancies exchange diffusion and the dominant Ni diffusion along the [1 0 0] direction. The doping of Ge in the cell increased the exchange energy barrier and thus inhibited the IMC development and coarsening trend. In three reliability tests, only 0.013 wt% Ge microalloying in Pb60Sn40 was able to reduce IMC thickness by an increment of 22.6~38.7%. The proposed Ge microalloying method in traditional PbSn solder could yield a prospective candidate for highly reliable applications.

Transformation behavior and inverse magnetocaloric effect in Ni45Co5Mn36.7In13.3-xGex melt-spun ribbons

In the present work the influence of Ge doping on crystal structure, microstructure, martensitic transformation (MT) and magnetocaloric effect (MCE) of Heusler-type Ni45Co5Mn36.7In13.3-xGex (x = 0, 2, and 3 at. %) metamagnetic shape memory alloys (MetaMSMAs) have been studied. Melt-spinning was used to prepare ribbons of these alloys since the ribbon shape ensures a high surface-to-volume ratio favoring a high heat exchange rate in a solid-state refrigeration. Furthermore, melt-spinning can induce a specific microstructure and stabilize metastable phases at room temperature. The ribbons were examined by X-ray diffraction at different temperatures, scanning electron microscopy, calorimetry, thermomagnetization, and magnetic field induced adiabatic temperature change measurements carried out across MT. It was found that Ge doping gave rise to enhanced antiferromagnetic interactions, stabilized martensitic phase, increased the MT temperature, causing larger magnetization jumps at MT and making narrower MT hysteresis. The x = 3 ribbon exhibited an inverse MCE at 303 K characterized by the isothermal magnetic entropy change value of |26.9|J/kgK at μ0H = 5 T and an adiabatic temperature change of ǀ1.5ǀ K at μ0H = 1.96 T. These values are comparable with the previously reported data on the Ni–Mn-based metamagnetic shape memory alloys in a bulk form.

Overcoming the doping limit in GaAs by ion implantation and pulsed laser melting

Most semiconductors exhibit a saturation of free carriers when heavily doped with extrinsic dopants. This carrier saturation or “doping limit” is known to be related to the formation of native compensating defects, which, in turn, depends on the energy positions of their conduction band minimum and valence band maximum. Here, we carried out a systematic study on the n-type doping limit of GaAs via ion implantation and showed that this doping limitation can be alleviated by the transient process of pulsed laser melting (PLM). For n-type doping, both group VI (S) and amphoteric group IV (Si and Ge) dopants were implanted in GaAs. For comparison, p-type doping was also studied using Zn as the acceptor. Implanted dopants were activated by the PLM method, and the results are compared to rapid thermal annealing (RTA). Our results reveal that for all n-type dopants, while implantation followed by the RTA results in a similar saturation electron concentration of 2–3 × 1018 cm−3, the transient PLM process is capable of trapping high concentration of dopants in the substitutional site, giving rise to a carrier concentration of >1019 cm−3, exceeding the doping limit of GaAs. However, due to scatterings from point defects generated during PLM, the mobility of n-type GaAs after PLM is low (∼80–260 cm2/V s). Subsequent RTA after PLM (PLM + RTA) is able to remove these point defects and recover the mobility to ∼1000–2000 cm2/V s. The carrier concentrations of these PLM + RTA samples are reduced but are still a factor of 3 higher than RTA only GaAs. This can be understood as the dopants are already incorporated in the substitutional site after PLM; they are less likely to be “deactivated” by subsequent RTA. This work is significant to the understanding of doping mechanisms in semiconductors and provides a means for device applications, which require materials with ultra-high doping.

Improved performance of kesterite Cu2ZnSn(S,Se)4 thin film solar cells by Ag/Ge co-doping

Cation doping is an important approach to improve the performance of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. Since different cation dopant has different effects on the defects and crystallization of CZTSSe absorber, it is expected to achieve better device performance via the synergistic effects of double cation co-doping compared with the single cation doping. Herein, we investigated the effects of Ag/Ge co-doping on CZTSSe solar cells by doping Ge in an already optimized Ag-alloyed CZTSSe (ACZTSSe). It is found that incorporating a small amount of Ge can further improve the crystallinity and minority carrier lifetime of ACZTSSe. The low-temperature photoluminescence results reveal that the Ge doping primarily suppressed the SnZn defects in ACZTSSe, thereby further boosting the device performance. However, higher Ge doping concentration can lead to a discontinuous surface morphology, which is believed to be related with the relatively low melting temperature and double-layered structure of ACZTSSe absorber. The deteriorated surface morphology results in photocurrent loss in the near-infrared region and decreased fill factor. As the Ge doping ratio increases, there is a balance between the defects and morphology. A champion power conversion efficiency (PCE), 11.4%, was achieved for the Ag/Ge co-doped CZTSSe solar cells at Ge substitution rate of 3%. Compared with the single Ag doping, the average PCE was further promoted by 0.5% due to Ag/Ge co-doping.

A-site and B-site co-doped PrBaFe2O5+δ double perovskite as a symmetrical electrode of solid oxide fuel cell with potential of CO2 electrolysis

In this study, PrBa0.5Sr0.5Fe1.9Ge0.1O5+δ (PBSFG), the Sr and Ge doped PrBaFe2O5+δ (PBF), is investigated as a symmetrical electrode of solid oxide cells (SOCs). PBSFG has the potential to be a promising symmetrical electrode in SOCs owing to its high catalytic performance with redox stability. The concentration of oxygen vacancies and surface exchange coefficient of PBSFG are better than that of PBF. The results indicate that PBSFG exhibits not only adequate performance in the fuel cell, with a maximum power density of 1.05 W cm−2 at 800 °C, but also enhanced CO2 electrolysis performance, compared to the PBF. Specifically, in the CO2-electrolysis mode, a maximum current density of 825 mA cm−2 is measured at 850 °C and 1.5 V, which is substantially higher than that of 370 mA cm−2 measured for undoped PBF. These results demonstrate the effectiveness of Sr and Ge doping in PBF to improved CO2 electrolysis performance and notable fuel cell performance.

Physical mechanism of Ge doping enhanced Ruddlesden-Popper structure quasi-2D Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub> ceramic hybrid improper ferroelectricity

Hybrid improper ferroelectricity with quasi-two-dimensional (quasi-2D) structure has attracted much attention recently due to its great potential in realizing strong magnetoelectric coupling and room-temperature multiferroicity in a single phase. However, recent studies show that there appears high coercive field and low remnant polarization in ceramics, which severely hinders the applications of this material. In this work, high-quality Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub> and Sr<sub>3</sub>Sn<sub>1.99</sub>Ge<sub>0.01</sub>O<sub>7</sub> ceramics with a Ruddlesden-Popper (R-P) structure are successfully prepared, and their crystal structures and electrical properties are investigated in detail. It is found that the Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub> ceramic exhibits a lower coercive field that is close to that of Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub> single crystal. Moreover, via a small amount of Ge doping, the polarization reaches 0.34 μC/cm<sup>2</sup> for Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub> and 0.61 μC/cm<sup>2</sup> for Sr<sub>3</sub>Sn<sub>1.99</sub>Ge<sub>0.01</sub>O<sub>7</sub>. Combining crystal lattice dynamic studies, we analyze the Raman and infrared responses of the samples, showing the information about the tilting and rotation of the oxygen octahedra in the samples. The improved ferroelectricity after doping may be attributed to the increased amplitude of the tilt mode and the reduced amplitude of rotation mode. Besides, the enhanced ferroelectric properties through Ge doping and its mechanism are further investigated by the Berry phase approach and the Born effective charge method. Furthermore, via the UV-visible spectra, the optical bandgap is determined to be 3.91 eV for Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub> ceramic and 3.95 eV for Sr<sub>3</sub>Sn<sub>1.99</sub>Ge<sub>0.01</sub>O<sub>7</sub> ceramic. Using the Becke-Johnson potential combined with the local density approximation correlation, the bandgap is calculated and is found to be in close agreement with the experimental result. And the electronic excitations can be assigned to the charge transfer excitation from O 2p to Sn 5s (Ge 4s). The effects of Ge doping on the ability of Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub> to gain and lose electrons and the bonding strength of Sn-O bond are analyzed via two-dimensional charge density difference. In conclusion, this study provides insights into the synthesis method and modulation of ferroelectric properties of hybrid improper ferroelectrics Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub>, potentially facilitating their widespread applications in various capacitors and non-volatile memory devices.

Metalloid-doping in SMoSe Janus layers: first-principles study on efficient catalysts for the hydrogen evolution reaction

Spin-polarized first-principles calculations were carried out to explore whether B, Si, and Ge-doped SMoSe Janus layers can be used as potential catalysts in the hydrogen evolution reaction.

Germanium doping effect on the photoelectronic performance of alternating cations in the interlayer space GA(MA)3(Pb1−xGex)3I10

The pivotal role of Ge doping is found in finely adjusting the bandgap, enhancing carrier mobility, and improving optical-electronic properties and photovoltaic response.

Combined Radiation and Temperature Effects on Brillouin-Based Optical Fiber Sensors

The combined effects of temperature (from −80 °C to +80 °C) and 100 kV X-ray exposure (up to 108 kGy(SiO2)) on the physical properties of Brillouin scattering and losses in three differently doped silica-based optical fibers, with varying dopant type and concentration (4 wt%(Ge), 10 wt%(Ge) and 1 wt%(F)), are experimentally studied in this work. The dependencies of Brillouin Frequency Shifts (BFS), Radiation-Induced Attenuation (RIA) levels, Brillouin gain attenuation, Brillouin frequency temperature (CT) and strain (Cε) sensitivity coefficients are studied under X-rays in a wide temperature range [−80 °C; +80 °C]. Brillouin sensing capabilities are investigated using a Brillouin Optical Time Domain Analyzer (BOTDA), and several properties are reported: (i) similar behavior of the Brillouin gain amplitude decrease with the increase in the RIA; (ii) the F-doped and heavily Ge-doped fibers do not exhibit a temperature dependence under radiation for their responses in Brillouin gain losses. Increasing Ge dopant concentration also reduces the irradiation temperature effect on RIA. In addition, Radiation-Induced Brillouin Frequency Shift (RI-BFS) manifests a slightly different behavior for lower temperatures than RIA, presenting an opportunity for a comprehensive understanding of RI-BFS origins. Related temperature and strain sensors are designed for harsh environments over an extended irradiation temperature range, which is useful for a wide range of applications.

Reaction kinetics of photoelectrochemical water and 5-hydroxymethylfurfural oxidation on rutile nanorod photoanode with Ge doping and core/shell structure

A high-performance TiO2/Ge-TiO2 nanorod photoanode, with the synergistic effect of Ge doping and core/shell structuring on promoting charge separation, was used in the photoelectrochemical H2 production system. The TiO2/Ge-TiO2 photoanode exhibited >90% hole transfer efficiency at 1.23 V vs. RHE for water oxidation. Moreover, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated hydroxymethylfurfural (HMF) oxidation was achieved on the TiO2 photoanodes for the first time. Notably, the kinetics of HMF oxidation were slower compared to water oxidation, resulting in a higher Faraday efficiency (FEHMF) corresponding to a lower hole transfer efficiency. The oxidation of HMF on the TiO2 photoanodes was found to predominantly follow the pathway dominated by 2,5-diformylfuran (DFF). The FEHMF displayed variation on the TiO2 photoanodes, with Ge doping leading to a decrease by enhancing surface hydrophilia. However, this decrease was effectively compensated for by the overlay of the TiO2 shell. Consequently, the TiO2/Ge-TiO2 photoanode achieved the highest HMF conversion rate, which can be attributed to the accelerated production and conversion of DFF. This work expands the application of TiO2 photoanodes on biomass conversion and sheds light on the pathway and kinetic characteristics of TEMPO-mediated HMF oxidation processes.

Influence of Ge doping on the magnetic properties and microstructure of Fe-Si-B-P-Cu alloys prepared with industrial raw materials

With the increasing demand for energy efficiency and miniaturization, there is a growing need for magnetic materials with high saturation magnetic flux density (Bs) and low coercivity (Hc). Here, Fe82.3Si4B9P4-xCu0.7Gex (x = 0, 1, 2) nanocrystalline ribbons were prepared using industrial raw materials (IRMs). We found that appropriate Ge doping can optimize Bs by enhancing the crystallization volume fraction of α-Fe phase, and refine grain size by increasing the energy barriers for the growth of α-Fe and Fe(B, P) phases, which ultimately reduces Hc. However, Ge doping can also induce surface crystallization of the ribbons due to the enrichment of Cu elements. Excessive diffusion of Cu into the crystalline layer is not favorable for grain refinement, which deteriorates the soft magnetic properties of the ribbons.

Influence of Ge-doping on the collinear and non-collinear antiferromagnetic phases of Mn[formula omitted]Si[formula omitted] alloy

Effect of Ge-doping at the non-magnetic site (Si-site) of the Mn-based binary alloy Mn5Si3 has been explored through temperature-dependent x-ray diffraction, dc-magnetic, and electrical transport measurements. All the doped alloys show D88 type hexagonal structure with space group P63/mcm at room temperature and undergoes two structural distortions, hexagonal (P63/mcm) → orthorhombic (Ccmm) → orthorhombic (Cc2m), on cooling. The magnetic characters of these orthorhombic (Cc2m), orthorhombic (Ccmm), and hexagonal (P63/mcm) phases are non-collinear antiferromagnetic (AFM1), collinear antiferromagnetic (AFM2), and paramagnetic (PM), respectively. Doping of Ge results in a significant increase in the AFM1 to AFM2 transition temperature (TN1). However, the AFM2 to PM transition point remains unchanged. In addition, a reasonable increase in the critical field values of the AFM1 to AFM2 transition via another non-collinear antiferromagnetic phase (AFM1′) with increasing Ge concentration has been observed, indicating the strengthening of AFM1 and AFM1′ phases over the AFM2 phase. Such behaviors make the observation of unusual magnetic properties of undoped Mn5Si3 alloys, like inverted hysteresis loop (IHL) and thermomagnetic irreversibility (TI), more evident for these Ge-doped alloys. Further, this study unfolds the presence of conventional and inverse magnetocaloric effect and they found to decrease with Ge doping. An interesting interplay for positive and negative magnetoresistance has also been observed in all the studied alloys.

Doping of large amount tetravalent Ge ions into Fe2O3 structure and experimental results on modified structural, optical and electronic properties

We report the doping of high concentration of tetravalent Ge4+ ions (5 mol % for x = 0.05–30 mol % for x = 0.30) at the Fe3+ sites of Fe2-xGexO3 system by chemical coprecipitation route. The charge state of Fe and Ge ions has been modified into lower values, in addition to their normal +3 and + 4 states, to stabilize the rhombohedral phase of hematite (α-Fe2O3) structure. X-ray photoelectron spectra and optical band gap measurements indicated a combination of ionic and covalence character of metal-oxygen bonds as an effect of Ge doping in the hematite structure. The Ge doped hematite samples have exhibited semiconductor properties with band gap of 1.50–4.70 eV and remarkably enhanced electrical conductivity (σ ∼ 10−4 S/m) in comparison to α-Fe2O3 (10−11 S/m). The results confirmed the strategy of enhancing electrical conductivity in hematite structure by doping of tetravalent cations. The thermo-conductivity measurements using warming and cooling modes showed highly irreversible feature at higher temperatures. Some of the samples indicated metal-like state at lower temperature, in addition to semiconductor state at higher temperatures. It has been understood that combination of ionic and covalence character of the metal-oxygen bonds has played an important role in modifying the semiconductor properties in Ge doped Fe2O3 system.

Successive performance enhancement on a Ge-Ti codoped α-Fe2O3 with AlOOH modification photoanode for photoelectrochemical water splitting

The poor charge separation efficiency is the main limiting factor of the α-Fe2O3 photoanode for photoelectrochemical water splitting. In this study, we have discovered that the incorporation of Ge-Ti codoping and AlOOH modification strategies can greatly enhance the charge separation efficiency of the α-Fe2O3 photoanode. By introducing the Ti element, which possesses high conductivity, and further enhancing the charge transfer through Ge doping, we have achieved a synergistic inhibition of charge recombination in the Ge-Ti codoped α-Fe2O3. Additionally, the introduction of AlOOH through modification has led to an increase in the interface band bending, thereby enhancing charge separation by elevating the Fermi band level. Furthermore, through the secondary growth (shorted as SG) of undoped α-Fe2O3 and the incorporation of a NiFeOx cocatalyst, we have successfully adjusted the surface states and reduced the onset potential. Through the collaborative efforts of Ge-Ti codoping, SG, AlOOH modification, and NiFeOx catalysis, we have sequentially optimized the performance of the α-Fe2O3-based photoanode, resulting in an impressive photocurrent density of 3.46 mA cm−2 at 1.23 VRHE, as well as a low onset potential of 0.65 VRHE.

Installing Quaternary Germanium Centers in Sila-Diamondoid Cores via Skeletal Isomerization.

This manuscript describes skeletal isomerization strategies to install one to four quaternary germanium atoms in the sila-adamantane core, in a cluster analogy to precision germanium doping in silicon-germanium alloys. The first strategy embodies an inorganic variant of single-atom skeletal editing, where we use a sila-Wagner-Meerwein bond shift cascade to exchange a peripheral Ge atom with a core Si atom. We can install up to four Ge atoms at the quaternary diamondoid centers based on controlling the SixGey stoichiometry of our precursor. We find that bridgehead Ge centers can be selectively functionalized over bridgehead Si centers in SiGe adamantanes; we use this chemistry in conjunction with scanning tunneling microscopy break-junction (STM-BJ) measurements to show that Si8Ge2 adamantane wires give a 60% increase in single-molecule conductance compared with Si10 adamantanes. These studies describe the first quantum transport measurements in sila-diamondoid structures, and demonstrate how main-chain Ge doping can be used to increase electronic transmission in sila-diamondoid-based molecular wires.

Correlation between crystallite size, resistance to oxidation, and phase transformation of germanium-doped Fe3O4 nanocrystalline thin films by using a sputtering target of α-Fe2O3

We investigated the correlation between the crystallite size, resistance to oxidation, and phase transition of Ge-doped Fe3O4 nanocrystalline thin films. We prepared thin films on water-cooled glass substrates by radiofrequency sputtering with Ge-tipped α-Fe2O3 ceramic disks as targets. The addition of Ge caused a reductive phase transition from α-Fe2O3 with a corundum structure to Ge-doped Fe3O4 with an inverse spinel structure, resulting in a crystallite size of <10 nm. We annealed three samples with average sizes of 5, 8, and 10 nm by changing Ge addition concentrations at 673 K in air for up to 323 days until reaching near-thermal equilibrium. All samples maintained their magnetization at almost a constant value over long-term heat treatment. The results of Raman spectroscopy and optical transmittance spectroscopy suggest that there was a phase transition to Ge-doped γ-Fe2O3 at 5 nm, Ge-doped Fe3−δO4 with iron vacancies δ at 8 nm, and Ge-doped Fe3O4 at 10 nm. In other words, we retained Fe3O4 down to a relatively small crystallite size of 10 nm because of the improved oxidation resistance imparted by Ge doping.

Germanium monolayer doping: successes and challenges for the next generation Ge devices

The growing interest in nanoelectronics and photonics, combined with the development of new germanium-based devices, provide the impetus to develop new doping methods suitable to new germanium challenges. The monolayer doping technique is one of the most promising techniques for nanostructure doping, especially for the possibility to perform conformal doping on nanostructured materials, the complete absence of lattice damage, the high control of the dopant and the reduction of the stochastic doping effects. In this paper, works that develop the monolayer doping technique on germanium will be described and analyzed, highlighting advantages and disadvantages of different possible approaches to Ge doping and finally outlining the future steps for the implementation of monolayer doping technique on device manufacturing.