Change Of Conduction Type Research Articles

Dopant compensation in component-dependent self-doped Cs2SnI6 thin films grown with PLD at room temperature

Tetravalent tin (Sn4+)-based inorganic perovskite semiconductors like Cs2SnI6 are expected to replace lead-based perovskite counterparts due to advantages such as structural stability and environmental friendliness. In this paper, we reported the dopant compensation effect in the component-dependent self-doped (111)-oriented Cs2SnI6 thin films grown with pulsed laser deposition (PLD) at room temperature. The films were grown on (100)-SrTiO3 (STO) substrates at room temperature by PLD. Hall results of the Cs2SnI6 films with different components realizing by controlling the ratio of SnI4/CsI in the targets demonstrate a clear change of conductivity type from N-type to P-type, while the carrier concentration decreases from 1018 to 1013 and accordingly the film resistivity increases significantly from 3.8 to 2506 Ω cm. The defect-related optical fingerprints of Cs2SnI6 films were also investigated with temperature-dependent photoluminescence spectroscopy. At low temperatures of 10 K, the Cs2SnI6 films exhibit donor-bound (D0X) and donor-acceptor pair (DAP) emission, respectively, due to the self-doping effect. These results indicate that controlling the composition of the PLD target is a powerful way to tune the electrical properties of Cs2SnI6 films for possible applications in solar cells or X-ray detectors.

Impact of post deposition treatment on optoelectrical and microstructural properties of tin sulfide thin film for photovoltaic applications

Tin sulfide (SnS) has attracted significant interest due to its advantageous optoelectrical characteristics and abundant presence in nature. Post-deposition treatments (PDTs) are frequently employed to enhance the crystallinity of chalcogenide-based solar cells. This study examined the influence of the post-deposition heat treatment procedure on thermally evaporated SnS thin film. The post-deposition annealing process, as determined by XRD and AFM studies, supplies the necessary thermal energy for re-crystallization, potentially resulting in a modification of crystallite dimensions. The occurrence of Sn-S polytypes was examined using Raman and XPS studies. Annealing causes changes in the optical properties, as observed through optical analysis, which can be attributed to the improvement in crystallinity. Subjecting the material to annealing at temperature of 300 °C greatly improves both mobility and conductivity, while also causing a change in conduction type. The observed variations in conduction type are attributed to the differing ratios between the amounts of Sn2+ and Sn4+. This strategy offers a novel route for the fabrication of thin-film photovoltaic cells by using a p-type buffer layer.

Change in the gas sensing mechanism and improved sensing response on ion-irradiated palladium-graphene oxide nanocomposite

In this study, we synthesized Pd-graphene oxide (Pd-GO) nanocomposite layers on SiO2/Si substrates using chemical method. Pd-GO layers were treated with swift heavy ion irradiation (100 MeV Ag ions, 1013 ions/cm2). The structural properties of the pristine as well as the ion irradiated samples were investigated using synchrotron grazing incidence x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. XRD shows peaks corresponding to Pd (FCC, space group-Fd-3m), GO and synthetic graphite. The relative graphite peak intensities increased after ion irradiation, indicating reduction of GO. The sensor responses of nanocomposite layers towards exposure of 35 ppm H2 at 100 °C, were measured for several cycles. Ion-irradiated Pd-GO samples show enhancement in the sensing response of H2 gas by about 24% and with lower recovery times (25%), as compared to pristine Pd-GO nanocomposite samples. The change in type of conductivity from p-type gas sensing layer in pristine nanocomposite to n-type conductivity, along with an increase in conductivity (about 500 times) in ion irradiated samples were observed. The change in type of conductivity on ion-irradiation is attributed to the reduction of GO layer and the changes in conductivity on hydrogen exposure is explained due to hydrogen spill-over effect in the two-component system. The improvement in sensitivity upon ion-irradiation was due to the increase in concentration of structural defects due to electronic energy loss, as studied by SRIM simulation. This study points towards using ion induced electronic energy loss as a new tool for varying the gas sensing properties of GO based sensors.

High-mobility transport symmetry and effect of strain on electronic and optical properties in few-layer blue phosphorus

As a new type of 2D semiconductor, blue phosphorus (BP) is an ideal material for new electronic devices, whose performance can be compared with that of black phosphorus. The first principles method of DFT is applied to calculate electronic and optical properties of few-layer BP. By applying uniaxial strain, the deformation potential constant is calculated, and the value obtained is very small (∼0.36 eV in a monolayer), which is the main reason for the extremely high carrier mobility (up to 47.9 × 103cm2V−1s−1). By the partial charge analysis of band edge, the small deformation potential constant is attributed to the fact that wave function is very isolated along the lattice vector direction in valence band. From monolayer to four-layer BP, conductivity type changes from p to n, the band gap decreases and the position of the first absorbance peak red shifts. When biaxial strain is applied, band gap peak appears at the position where the compression is greater with the increase of layers. Tension or compression can cause the absorbance peak red shift or blue shift. In the visible light range, the value of the first peak performs well (3.6 %–7.9 %). 8 % compressive strain will increase the absorbance peak by 50 %–60 %. These results can provide theoretical support for few-layer BP as low power-consumption devices or photosensitive devices in the future.

Conductivity inversion of methyl viologen-modified random networks of single-walled carbon nanotubes

One of the challenges of using carbon nanotubes electronics is achieving precise control of the conductivity type. It is particularly difficult to obtain the n-type conductive nanotubes. One of the most common methods of CNTs modification allowing to change their conductivity type is chemical functionalization. This paper describes the results of studies on non-covalent modification of randomly oriented single-walled carbon nanotubes (SWCNT) layers with methyl viologen (MV), which allows for the change of the conductivity of SWCNT from p- to n-type. The properties of pristine and MV-modified SWCNT have been compared using Scanning Electron Microscopy, Raman spectroscopy, and X-ray Photoelectron Spectroscopy. The SWCNT conductivity type change was confirmed by photo-conductance under ultraviolet illumination and measurements in the field effect transistor configuration.

P‐Type Nb‐Doped MoS2 Layer for Solar Cell Application

Herein, under a H2S/Ar ambient, a p+‐type Nb‐doped MoS2 (MoS2:Nb) film is developed via a sulfurization for a cosputtered Mo–Nb metal precursor to be applied to chalcogenide thin‐film solar cells. With the [Nb]/([Nb] + [Mo]) compositional ratio, the surface roughness and growth rate increase with the domination and diminishment of the (100) and (002) planes, respectively. By increasing the [Nb]/([Nb] + [Mo]) compositional ratio from 0 to 0.06, simultaneously, the carrier density of the MoS2:Nb films increases from 2.9 × 1016 up to 3.7 × 1020 cm−3, and the conductivity type changes from n‐type to p‐type as a result of the Nb atoms acting as acceptors. The ionization energy indicates a transition from a broad Nb acceptor band to a vacuum level for the highly doped p‐type MoS2:Nb films. Thus, by utilizing the p+‐type MoS2:Nb intermediate layer in the chalcogenide solar cells, a suppressed carrier recombination at the Mo back electrode/chalcogenide absorber interface by a back surface field is expected. Overall, it is believed that the obtained findings in this work can help boost the power conversion efficiency of the chalcogenide solar cells owing to the back junction modification.

Electrical and Optical Properties of Indium and Lead Co-Doped Cd0.9Zn0.1Te.

We have investigated the electrical and optical properties of Cd0.9Zn0.1Te:(In,Pb) wafers obtained from the tip, middle, and tail of the same ingot grown by modified vertical Bridgman method using I-V measurement, Hall measurement, IR Transmittance, IR Microscopy and Photoluminescence (PL) spectroscopy. I-V results show that the resistivity of the tip, middle, and tail wafers are 1.8 × 1010, 1.21 × 109, and 1.2 × 1010 Ω·cm, respectively, reflecting native deep level defects dominating in tip and tail wafers for high resistivity compared to the middle part. Hall measurement shows the conductivity type changes from n at the tip to p at the tail in the growth direction. IR Transmittance for tail, middle, and tip is about 58.3%, 55.5%, and 54.1%, respectively. IR microscopy shows the density of Te/inclusions at tip, middle, and tail are 1 × 103, 6 × 102 and 15 × 103/cm2 respectively. Photoluminescence (PL) spectra reflect that neutral acceptor exciton (A0,X) and neutral donor exciton (D0,X) of tip and tail wafers have high intensity corresponding to their high resistivity compared to the middle wafer, which has resistivity a little lower. These types of materials have a large number of applications in radiation detection.

Regulation of absorption coefficients between multi-photon and free-carrier in PbTe films by deposition temperature

We investigate the effects of deposition temperature on a crystal structure and electrical and optical properties of PbTe thin films sputtered on BaF2 (111). We observe that with the increase in deposition temperature, the grain size increases, and when it reaches 300 °C, the grain size reaches the maximum, and the preferred orientation begins to change. At 400 °C, the lattice mismatch rate decreases from 4.2% to 3.6% due to lattice contraction caused by reevaporation, and the conduction type changes from p-type dominated by a mismatch strain defect to n-type dominated by a Te vacancy. These changes lead to the interplay of various absorption mechanisms. We find that, in addition to the overall absorption coefficient curve significantly changing with deposition temperature, more importantly, the contribution of various internal absorption mechanisms to the below bandgap absorption spectrum does no longer synchronize. Instead, the contribution of an acoustic phonon to free-carrier absorption (FCA) decreases, while the relative contribution of optical phonon, impurity, two-photon absorption (2PA), and three-photon absorption (3PA) increases. This regulation effect reaches its maximum at 300 °C, which of various absorption mechanisms at 300 °C are 6.3, 11.6, 4.4, and 14.7 times higher than that at 20 °C corresponding to an optical phonon, impurity, 2PA, and 3PA processes, respectively. These results indicate that it should be possible to regulate the FCA, 2PA, and 3PA processes by changing the deposition temperature, thus making them suitable for applications in optoelectronic devices.

Impact of conductivity type change in InAs/GaSb superlattice on low frequency noise of photoconductive long-wavelength infrared detectors

This Letter focuses on the 1/f noise properties of InAs/GaSb superlattice (SL), which is a promising material for infrared radiation detection and represents one of the alternatives to well-established bulk HgCdTe material. The InAs/GaSb SL material changes the conductivity type at temperature T ≈ 190 K, which has been correlated with measured 1/f noise. It was shown that 1/f noise comes from resistance fluctuations of linear noise sources. According to the electronic transport and 1/f noise models, the observed 1/f noise is connected with the hole conductivity component rather than the electron conductivity component, which is absent or at least immeasurable, even though electron conductivity governs the total conductivity of the InAs/GaSb SL. In the high-temperature region, the 1/f noise of InAs/GaSb SL is significantly smaller than that of InAs/InAsSb SL. The results favor InAs/GaSb SL material over InAs/InAsSb SL for photoconductive infrared detectors operating at room temperature.

Percolation effects and self-organization processes in cold-pressed Bi2(Te1−xSex)3 solid solutions

Abstract It was established that the dependences of thermoelectric and mechanical properties of cold-pressed Bi2(Te1−xSex)3 alloys on composition (x = 0–0.07) exhibit a non-monotonic behavior in certain concentration ranges: an anomalous decrease in the Seebeck coefficient, thermoelectric power factor, and microhardness, and increase in electrical conductivity with increasing x. We observed similar anomalies earlier for cast Bi2(Te1−xSex)3 alloys and explained them by percolation and self-organization phenomena. Thus, the existence of the anomalies does not depend on the method of sample preparation. However, in pressed samples as compared to cast ones conductivity type changes from p to n and thermoelectric power factor increases.

P-n Transition-Enhanced Sensing Properties of rGO-SnO2 Heterojunction to NO2 at Room Temperature

RGO-SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> heterojunction has been extensively studied as an efficient sensitive material, while its sensing mechanism in surface chemical system is still needed to be concerned. The aim of this work is to evaluate the effects of rGO and materials processing on surface sites of nanocrystalline tin dioxide and room-temperature sensitivity to NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Gas-sensitive heterojunction of tin dioxide with 2-dimensional rGO has been synthesized by a one-step hydrothermal method. Contrastive researches about composition, microstructure and surface species of hydrothermalobtained pristine SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , rGO-SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> hybrids were performed. Further reduction of rGO in hydrothermal composite with a post-treatment at over 100 °C has been found to affect the hydrophilicity and electrical conduction of rGO-SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> composite. Sensitivity of rGO-SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> to 2-8 ppm NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> with fast response was demonstrated at room temperature, while the abrupt change of conductivity type of hydrothermal-obtained rGO-SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> heterojunction from p-type to n-type was observed after post-anneal treatment. The conductive type conversion was discussed to be closely related to the higher reduction degree of rGO and enhanced hydrophobic surface of rGO-SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> heterojunction.

A study on defect annealing in GaAs nanostructures by ion beam irradiation

In this study, annealing of deep level (EL2) defect in gallium arsenide (GaAs) nanostructures by argon ion beam irradiation has been reported. GaAs nanodots of diameter ranging from 15 to 22 nm were deposited on silicon substrates using the ions of GaAs generated by hot, dense and extremely non-equilibrium argon plasma in a modified dense plasma focus device. GaAs nanodots thus obtained were irradiated by $$\hbox {Ar}^{2+}$$ ion beam of energy 200 keV with varying ion fluences from $$1 \times 10^{13 }$$ to $$5 \times 10^{15}$$ ions $$\hbox {cm}^{-2}$$ in the low energy ion-beam facility. The ion-beam irradiation transformed the as-deposited GaAs nanodots into uniform GaAs nanostructured films of thickness $$\sim $$30 nm. The obtained nanostructured films are polycrystalline with paucity of arsenic antisite (EL2) deep level defect. The excess arsenic present in the as-deposited GaAs nanodots is the main cause of EL2 defect. Raman and photoluminescence measurements of GaAs nanostructured films indicates removal of excess arsenic, which was present in as-deposited GaAs nanodots, thereby suggesting annealing of EL2 defect from the ion-irradiated GaAs nanostructured films. The change in conductivity type from n- to p-type obtained from Hall measurement further confirms annealing of EL2 defects. The ion-irradiated GaAs nanostructured films have low leakage current due to removal of defects as obtained in current–voltage study, which corroborate the annealing of EL2 defect. The defect-free GaAs nanostructured films thus obtained have potential applications in fabrication of highly efficient optoelectronic and electronic devices.

Enhanced optical and electrical performance of Ge1−xSnx/Ge/Si(100) (x = 0.062) semiconductor via inductively coupled H2 plasma treatments

The structural, electrical and optical properties of a unintentionally doped Ge1−xSnx (x = 6.2%) alloy semiconductor both as-grown and after a hydrogen plasma treatment or ‘hydrogen passivation’ are investigated by high resolution x-ray diffraction, atomic force microscopy, and temperature-dependent Hall-effect and photoluminescence (PL) measurements. The samples were grown via reactions of SnD4 and Ge3H8 on Ge buffered Si wafers at 305 °C and subsequently subjected to a hydrogen plasma environment generated using an inductively coupled H2 approach (ICP). The plasma treatments showed no appreciable change in the structural, compositional and morphological properties of the samples indicating no measurable degradation of the materials quality has occurred. However, the H passivation significantly alters the electrical activity of as-grown defects and impurities in the epilayer, resulting in electrical conductivity of passivated sample that is more than 2 times higher at 300 K and 30 times higher at 10 K. The as-grown samples showed conduction-type changes with temperature (manifested by singularities in the apparent carrier concentrations around 14 and 255 K), while the background n-type carrier concentration of the hydrogen treated analogs varied smoothly with temperature. In particular at 300 K, the carrier concentration was reduced from the background 4.61 × 1017 cm−3 in the as-grown material to 5.68 × 1016 cm−3 in the H treated counterpart due to potential passivation of deleterious point defects, a highly desirable outcome for effective device performance. The room temperature PL intensity increased ∼5 times (more than 3 times at 5 K) upon hydrogen treatment due to electrical passivation of deep acceptor states. Hydrogen plasma treatments are thus found to enhance the electrical and optical responses of the samples, suggesting that conventional ICP treatments could be used as a processing step to improve the properties of newly developed Sn-based group IV semiconductors using straightforward and relatively low temperature protocols.

The influence of Ag doping and annealing on phase, structural and carrier transport characteristics of CIS thin films

Abstracts The un-doped and Ag-CIS thin films were deposited on quartz glass substrates by single source thermal evaporation method. Then, some CIS films were annealed in vacuum or N2 atmosphere from 350 °C to 550 °C. The results of XRD patterns showed the phase compositions of CIS thin films were changed with the increase of annealing temperature. Meanwhile, the results of Raman measurement confirmed a dramatic transition from CA phase to CH phase. Furthermore, the Ag atoms could promote the recrystallization process and the transition from CA phase to CH phase, which might result in the improvement of optical-electrical properties of CIS film. The transient photocurrent of the CIS-3 sample annealed at 450 °C was higher than those of other samples, which might be related to the good crystal quality. The results of I-V curves confirmed the N-type conduction of CIS-3 films, which was consistent with the results of EDS measurement. The C-V results of CIS-2 films also were the same as the results of EDS measurement. Furthermore, for the CIS-2 samples, with increase of annealing temperature, the change of conduction type may be related to the S element volatilization under vacuum situation and the decomposition of the substitutional defects AgIn.

The Lateral Photovoltaic Effect in the Fe/SiO&lt;sub&gt;2&lt;/sub&gt;/ Si Structure with Different Silicon Conductivity Type

We report on the results of the study of the lateral photovoltaic effect in the Fe/SiO2/Si structures with n-and p-type silicon. It is found that in both cases the photovoltage signal varies linearly when the light spot moves between the electrodes. It is established that the sensitivity of lateral photovoltaic effect in Fe/SiO2/n-Si and Fe/SiO2/р-Si structures is 32.3 and 14.7 mV/mm, respectively. When the silicon conductivity type changes, there is an inversion of photovoltage polarity as a result of the opposite direction of the built-in electrical field at the SiO2/Si interface. It was found that the response time in the Fe/SiO2/n-Si structure is 4.2 times faster than in the Fe/SiO2/p-Si structure due to the presence of an inversion layer in this structure.

Effect of Gallium Doping on the Characteristic Properties of Polycrystalline Cadmium Telluride Thin Film

Ga-doped CdTe polycrystalline thin films were successfully electrodeposited on glass/fluorine doped tin oxide substrates from aqueous electrolytes containing cadmium nitrate (Cd(NO3)2·4H2O) and tellurium oxide (TeO2). The effects of different Ga-doping concentrations on the CdTe:Ga coupled with different post-growth treatments were studied by analysing the structural, optical, morphological and electronic properties of the deposited layers using x-ray diffraction (XRD), ultraviolet–visible spectrophotometry, scanning electron microscopy, photoelectrochemical cell measurement and direct-current conductivity test respectively. XRD results show diminishing (111)C CdTe peak above 20 ppm Ga-doping and the appearance of (301)M GaTe diffraction above 50 ppm Ga-doping indicating the formation of two phases; CdTe and GaTe. Although, reductions in the absorption edge slopes were observed above 20 ppm Ga-doping for the as-deposited CdTe:Ga layer, no obvious influence on the energy gap of CdTe films with Ga-doping were detected. Morphologically, reductions in grain size were observed at 50 ppm Ga-doping and above with high pinhole density within the layer. For the as-deposited CdTe:Ga layers, conduction type change from n- to p- were observed at 50 ppm, while the n-type conductivity were retained after post-growth treatment. Highest conductivity was observed at 20 ppm Ga-doping of CdTe. These results are systematically reported in this paper.

Influence of Oxidation on Electrical Properties of Compacted Cu Nanopowders.

The phase composition and electrical transport properties of Cu powder obtained by electric spark dispersion and the pellets manufactured from this powder were studied by X-ray phase analysis and electric resistance measurements. The compacted powders were annealed in pure Ar atmosphere. It was shown that electrical resistance of the compacted Cu specimens essentially depends on the annealing temperature. In particular, the electrical resistance of the pellet after annealing at 873 K decreases on heating at low temperatures (semiconducting mechanism). As the temperature is increased, semiconducting behavior of resistivity is altered for metallic one. This change of conductivity type is ascribed to formation of metallic oxide and modification of its content during annealing.

Microstructures and optoelectronic properties of CuxO films deposited by high-power impulse magnetron sputtering

Herein, a novel method of high-power impulse magnetron sputtering (HiPIMS) was used to prepare Cu2O thin films, which were deposited at ambient temperature without further thermal treatment. The films with varying optoelectronic properties as a function of oxygen flow ratio (fO2) were investigated. The results demonstrate that the film's performances are dependent on the film's composition and their crystallinity, which is influenced by the oxygen flow ratio. Cu2O-dominated films were fabricated in the oxygen flow range between 12.5% and 35%, whose values were used to determine their optoelectronic properties. Consequently, the films optoelectronic properties can be controlled by adjusting oxygen flow ratio. At low oxygen flow ratio (fO2 ≤ 10%), Cu-dominated films present n-type conductivity. With oxygen flow ratio increasing to above 15%, the films conductivity type changes from n-type to p-type due to the majority phase in the films changing from Cu to Cu2O. Meanwhile, the film's transmittance improves significantly from 0.28% for fO2 of 2.5% to the maximum value of 58.77% for fO2 of 30% resulting from the phase's transition upon increasing the oxygen flow ratio. When the oxygen flow ratio is at about 20%, a Cu2O film with optimal p-type conductivity of approximately 0.4 S × cm−1 is achieved at room temperature, which is the highest p-type conductivity reported in Cu2O film for the last few years.

Conductive SiC ceramics fabricated by spark plasma sintering

Bulk SiC ceramics were fabricated by spark plasma sintering, and the effects of Y2O3 addition on the structural and electrical properties were investigated. Raman spectroscopy revealed that SiC specimens with low Y2O3 content (0.01 and 0.05wt%) contained a graphitic phase (1580 and 2710cm−1) which was insignificant for high Y2O3 content (1.0 and 5.0wt%). Carbon-rich SiC specimens exhibited p-type conduction character, while others exhibited n-type character. The p- and n-type SiC specimens had electrical resistivities around 10−2Ωcm but exhibited photoluminescence spectra quite different from each other. The p-type character is primarily attributable to silicon vacancies (VSi), while the n-type character is ascribed to nitrogen substitution in carbon sites (NC) of the zincblende lattice. The change in conduction type with yttria addition in the SiC specimen can be understood in terms of a competition between the densities of VSi and NC.

Optical Properties and Boron Doping-Induced Conduction-Type Change in SnO2 Thin Films

Boron-doped tin oxide (BTO) films, 0–5 at.% B, were prepared by sol–gel dip coating on a glass substrate. Dried precursor films were post-annealed at a temperature between 400°C and 750°C for 2 h. The obtained BTO thin films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible light (UV–Vis) spectrometry, a four-point probe, and Hall-effect and Seebeck-effect measurements. Optimal optical transmittance was achieved for post-annealed BTO thin film at 700°C. XRD results show a rutile SnO2 structure with a preferred (110) orientation for all the films. The grain size is 47–21 nm, which reduces with increasing B contents. The optical transmittance is 84.6–88.5% at a wavelength of 550 nm and optical band gap of 3.52–3.75 eV. Electrical resistivity is (3.4–8.2) × 10−3 Ω cm, and figure of merit (0.9–4.3) × 10−3 Ω−1. Carrier concentration is (0.97–7.4) × 1020 cm−3 and mobility (2.5–7.8) cm2 V−1 s−1. BTO film with 4 at.% B shows an optimal combination of properties. Conduction type changes from n- (undoped) to p- (1–4 at.% B), then to n-types (5 at.% B), as evidenced from Hall-effect and Seebeck-effect measurements. This is explained by doping-generated defects and phase separations of Sn3O4 and B2O3.