Role of microstructure in electronic transport behavior of highly crystallized undoped microcrystalline Si Films

Ram, Sanjay K.; Kumar, Satyendra; Cabarrocas, Pere Roca i

doi:10.1016/j.tsf.2007.01.003

Cited by 11 publications

(11 citation statements)

References 59 publications

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“…Defects at grain or column boundaries in c-Si: H will determine the material quality in agreement with earlier interpretations on the relationships between deposition process, structure and defects, and electronic quality and device performance. 71,80,81 An analytic relationship such as in the case of a-Si: H is not found. The heterogeneous structure composition in c-Si: H and different defect annealing kinetics in the crystalline and amorphous regions, respectively, is suggested to play an important role here providing inhomogeneous distribution of the defects in c-Si: H after irradiation.…”

Section: B Conductivity In Intrinsic C-si: Hmentioning

confidence: 97%

Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

et al. 2009

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The influence of dangling-bond defects and the position of the Fermi level on the charge carrier transport properties in undoped and phosphorous doped thin-film silicon with structure compositions all the way from highly crystalline to amorphous is investigated. The dangling-bond density is varied reproducibly over several orders of magnitude by electron bombardment and subsequent annealing. The defects are investigated by electron-spin-resonance and photoconductivity spectroscopies. Comparing intrinsic amorphous and microcrystalline silicon, it is found that the relationship between defect density and photoconductivity is different in both undoped materials, while a similar strong influence of the position of the Fermi level on photoconductivity via the charge carrier lifetime is found in the doped materials. The latter allows a quantitative determination of the value of the transport gap energy in microcrystalline silicon. The photoconductivity in intrinsic microcrystalline silicon is, on one hand, considerably less affected by the bombardment but, on the other hand, does not generally recover with annealing of the defects and is independent from the spin density which itself can be annealed back to the as-deposited level. For amorphous silicon and material prepared close to the crystalline growth regime, the results for nonequilibrium transport fit perfectly to a recombination model based on direct capture into neutral dangling bonds over a wide range of defect densities. For the heterogeneous microcrystalline silicon, this model fails completely. The application of photoconductivity spectroscopy in the constant photocurrent mode ͑CPM͒ is explored for the entire structure composition range over a wide variation in defect densities. For amorphous silicon previously reported linear correlation between the spin density and the subgap absorption is confirmed for defect densities below 10 18 cm −3 . Beyond this defect level, a sublinear relation is found i.e., not all spin-detected defects are also visible in the CPM spectra. Finally, the evaluation of CPM spectra in defect-rich microcrystalline silicon shows complete absence of any correlation between spindetected defects and subband gap absorption determined from CPM: a result which casts considerable doubt on the usefulness of this technique for the determination of defect densities in microcrystalline silicon. The result can be related to the inhomogeneous structure of microcrystalline silicon with its consequences on transport and recombination processes.

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Section: B Conductivity In Intrinsic C-si: Hmentioning

confidence: 97%

Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

et al. 2009

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“…But the nature of density of gap states (DOS) of   -Si:H c  -Si:H c  is still not well understood, because of structural heterogeneity of this material. Recently, Sanjay Ram et al [2,3] proposed numerical simulation modelling using Shockley-Read statistics in steady state conditions which describe the effective DOS picture in .…”

Section: Introductionmentioning

confidence: 99%

Density of States in Intrinsic and n/p-Doped Hydrogenated Amorphous and Microcrystalline Silicon

Larbi¹,

Abdelkader²,

Sib³

et al. 2011

JMP

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Gap states in amorphous hydrogenated silicon (a-Si:H) doped and microcrystalline silicon doped n and p were examined by analysis of subgap absorption spectra obtained by the Constant Photocurrent Method (CPM) and the Photothermal Deflection Spectroscopy (PDS). Assuming a Gaussian distribution of defect states in the gap, broad distribution of states was found in a-Si:H and doped a-Si:H. A dependence of the defect concentration on Fermi energy was detected and analysed by thermodynamic model of defect formation in a-Si:H.

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“…Furthermore thinner (less than about 50 nm) samples exhibit enhanced quantum confinement effects [6], which vanishes in thicker films because of increased grain size [7]. Enhanced quantum confinement offers additional properties, such as increased carrier mobility [8] which could have advantages when used in large area applications.…”

Section: Introductionmentioning

confidence: 99%

“…Given that the structure of a-Si:H is independent of thickness, known that the structure of nc-Si:H evolves with thickness, including surface roughness [17], grain size and crystal fraction [7], and consequently grain boundary interface area. Therefore conductivity studies of thick nc-Si:H films are not directly applicable to thinner films, because the results are strongly influenced by the surface effects and cannot be directly used for investigating bulk properties.…”

Section: Introductionmentioning

confidence: 99%

Light-induced metastability in thin nanocrystalline silicon films

Bauža

Mandal

Ahnood

et al. 2009

Philosophical Magazine

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Role of microstructure in electronic transport behavior of highly crystallized undoped microcrystalline Si Films

Cited by 11 publications

References 59 publications

Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

Density of States in Intrinsic and n/p-Doped Hydrogenated Amorphous and Microcrystalline Silicon

Light-induced metastability in thin nanocrystalline silicon films

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