Microstructure, optical, and electrical properties of p-type SnO thin films

Guo, Wang; Fu, Lei; Zhang, Y.; Zhang, K.; Liang, Lingyan; Liu, Z. M.; Cao, Hu; Pan, Xiaoqing

doi:10.1063/1.3277153

Cited by 170 publications

(148 citation statements)

References 11 publications

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“…As seen in Figure 5(b), the optical bandgaps of the Ag-doped SnO thin films were estimated to be approximately 2.7, 2.65, 2.63, and 2.6 eV for Ag dopant contents of 0%, 1%, 3%, and 5%, respectively. These values closely match the reported optical bandgap of tetragonal SnO (2.0-3.0 eV) [6,7]. The optical bandgap of the SnO thin films tends to decrease with increasing dopant concentration.…”

Section: Resultssupporting

confidence: 78%

“…However, there are only a few literature reports on metal-doped SnO, and the doping effects thereof [5]. Guo et al speculated that the increase in the concentration of Y doping in the SnO [6], the deterioration of crystallinity, and the increase in optical bandgap of SnO have been observed. Ahn et al reported that increasing Mg doping concentration in SnO thin films results in lower crystallite size and higher resistance [7].…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Ag-Doped p-Type SnO Thin Films Prepared by DC Magnetron Sputtering

Pham

Giang

Tran

et al. 2017

Journal of Nanomaterials

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Crystalline structure and optoelectrical properties of silver-doped tin monoxide thin films with different dopant concentrations prepared by DC magnetron sputtering are investigated. The X-ray diffraction patterns reveal that the tetragonal SnO phase exhibits preferred orientations along (101) and (110) planes. Our results indicate that replacing Sn 2+ in the SnO lattice with Ag + ions produces smaller-sized crystallites, which may lead to enhanced carrier scattering at grain boundaries. This causes a deterioration in the carrier mobility, even though the carrier concentration improves by two orders of magnitude due to doping. In addition, the Agdoped SnO thin films show a p-type semiconductor behavior, with a direct optical gap and decreasing transmittance with increasing Ag dopant concentration.

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Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Characterization of Ag-Doped p-Type SnO Thin Films Prepared by DC Magnetron Sputtering

Pham

Giang

Tran

et al. 2017

Journal of Nanomaterials

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“…Doping with Y and Sb has also been shown to offer improved p-and n-type properties, respectively, 78,83,84 and, consequently, devices which show bipolar operation have been reported, although the mechanism of p-type enhancement by Y is unclear.…”

Section: 81mentioning

confidence: 99%

“…Cao and co-workers [83][84][85]88,89 favour a two-step process involving the electron beam evaporation (EBE) of SnO 2 on p-type silica, followed by thermal annealing at temperatures between 300 and 600 C. Conversely, the epitaxial process , 90 respectively. However, unlike the latter approaches, EBE and PLD are suggested to be less amenable to large-scale device production.…”

Section: 85mentioning

confidence: 99%

Understanding the defect chemistry of tin monoxide

et al. 2013

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Tin monoxide has garnered a great deal attention in the recent literature, primarily as a transparent p-type conductor. However, due to its layered structure (dictated by non-bonding dispersion forces) simulation via density functional theory often fails to accurately model the unit cell. This study applies a PBE0-vdW methodology to accurately predict both the atomic and electronic structure of SnO. Empirical van der Waals corrections improve the structure, with the calculated c/a ratio matching experiment, while the PBE0 hybrid-DFT method gives accurate band gaps (0.67 and 2.76 eV for the indirect and direct band gaps) and density of states which are in agreement with experimental spectra. This methodology has been applied to the simulation of the native intrinsic defects of SnO, to further understand the conductivity. The results indicate that n-type conductivity will not arise from intrinsic defects and that donor doping would be necessary. For p-type conduction, the Sn vacancy is seen to be the source, with the 0/À1 transition level found 0.39 eV above the valence band maximum. By considering the formation energies and transition levels of the defects at different chemical potentials, it is found that the p-type conductivity is sensitive to the O chemical potential. When the chemical potential is close to its lowest value (À2.65 eV here), the oxygen vacancy is stabilized which, whilst not leading to n-type conduction, could reduce p-type conduction by limiting the formation of hole states.

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“…5,12−14 However, the previous reports on doping effects are not consistent with each other. Guo et al reported that doping in SnO with large size dopants such as Sb or Y enhances their hole mobilities and hole concentrations, 13 the latter of which is opposite to usual concept of aliovalent ion doping (i.e., substitutions of the Sn 2+ sites by Sb 3+ /Y 3+ ions are expected to be n-type doping). In contrast, Hosono et al gave a clear evidence that Sb 3+ doping decreases the hole mobility and the hole concentration in SnO and finally converts the carrier polarity to n-type.…”

mentioning

confidence: 96%

Effects of Pb Doping on Hole Transport Properties and Thin-Film Transistor Characteristics of SnO Thin Films

Liao

Xiao

Ran

et al. 2015

ECS J. Solid State Sci. Technol.

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Effects of Pb doping on the microstructural, optical, and hole transport properties of Sn 1−xf Pb xf O films fabricated by pulsed laser deposition were investigated. It was found that Pb was not solved in bulk ceramic samples, while solved up to x f = 0.035 in the thin films. The Pb doping enlarged the optical bandgap, decreased the hole concentration, and reduced the Hall mobility (μ Hall , from 1.95 to 0.68 cm 2 V −1 s −1 up to x f = 0.035) as x f increased. The field-effect mobility in thin-film transistors also decreased with x f (μ lin , from 0.34 to 0.0024 cm 2 V −1 s −1 ), but the deterioration of μ lin was significantly larger than that of μ Hall . It is speculated that the deterioration of μ Hall would be due to the increase in grain boundary potential barriers. Oxide semiconductors have attracted considerable attention as next-generation channel materials to replace amorphous silicon and polycrystalline silicon for thin-film transistors (TFTs), because of their high electron mobilities >10 cm 2 V −1 s −1 and excellent electrical properties due to the large bandgaps.1−3 However, the reported oxide-based TFTs with excellent performance show n-type characteristics only. The lack of high-performance p-type oxide-based TFTs impedes the realization of transparent low-power-consumption complementary circuits in various TFT applications. 4,5 It is known that the valence band maximum (VBM) of most oxide semiconductors is mainly composed of fully occupied 2p orbitals of oxygen ions with a large electronegativity. 5,6 Hence the dispersion of the VBM band is in general small (i.e., the hole effective mass is large) and the ionization potential is large (i.e., the holes are energetically unstable), causing difficulty in p-type doping for oxide semiconductors.Fortunately, effective p-type doping and relatively high hole mobility is attained in SnO due to the hole contribution through the VBM composed of 5s 2 orbitals of Sn 2+ . 5,7 However, SnO TFTs generally operate in the depletion mode and have a high off-state current owing to the high hole concentration and the low resistivity of the SnO films.7−11 It is reported that the conductivity in SnO is related to tin vacancy and controllable also by impurity doping.5,12−14 However, the previous reports on doping effects are not consistent with each other. Guo et al. reported that doping in SnO with large size dopants such as Sb or Y enhances their hole mobilities and hole concentrations, 13 the latter of which is opposite to usual concept of aliovalent ion doping (i.e., substitutions of the Sn 2+ sites by Sb 3+ /Y 3+ ions are expected to be n-type doping). In contrast, Hosono et al. gave a clear evidence that Sb 3+ doping decreases the hole mobility and the hole concentration in SnO and finally converts the carrier polarity to n-type. 5Liang et al. demonstrated that doping of SnO with Y decreases the field-effect mobility but suppresses the off-state current in SnO TFTs, even though the mechanism for the reduction in the off-state current is not clarified.14 Like SnO, ...

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Microstructure, optical, and electrical properties of p-type SnO thin films

Cited by 170 publications

References 11 publications

Characterization of Ag-Doped p-Type SnO Thin Films Prepared by DC Magnetron Sputtering

Characterization of Ag-Doped p-Type SnO Thin Films Prepared by DC Magnetron Sputtering

Understanding the defect chemistry of tin monoxide

Effects of Pb Doping on Hole Transport Properties and Thin-Film Transistor Characteristics of SnO Thin Films

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