Carrier mobilities in microcrystalline silicon films

Bronger, Torsten; Carius, R.

doi:10.1016/j.tsf.2006.11.091

Cited by 20 publications

(13 citation statements)

References 9 publications

(11 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The exponent (α) Contributed Article of 0.5 is of interest since the direct proportionality N S CE ∝ n is observed [9,10] and one would expect the same for N S CE and σ dark . It has been proposed that α < 1 because of reduction in mobility (µ) at low doping level [9] and dependence of µ on n has been reported for the µc-Si:H with PH 3 -doping level in the range of 1…100 ppm [22], that approximately corresponds to the conditions in our study. In [22] µ is directly proportional to n for medium crystallinity samples while µ is nearly proportional to n 0.5 in highly crystalline material.…”

Section: Discussionsupporting

confidence: 80%

“…It has been proposed that α < 1 because of reduction in mobility (µ) at low doping level [9] and dependence of µ on n has been reported for the µc-Si:H with PH 3 -doping level in the range of 1…100 ppm [22], that approximately corresponds to the conditions in our study. In [22] µ is directly proportional to n for medium crystallinity samples while µ is nearly proportional to n 0.5 in highly crystalline material. The direct dependence µ ∝ n implies σ dark ∝ n 2 which explains the proportionality N S CE ∝ σ dark 0.5 (given that N S CE ∝ n) found over the whole crystallinity range.…”

Section: Discussionsupporting

confidence: 80%

See 1 more Smart Citation

Variation of the Fermi level in n‐type microcrystalline silicon by electron bombardment and successive annealing: ESR and conductivity studies

Astakhov¹,

Carius²,

Petrusenko³

et al. 2010

Phys. Status Solidi (c)

View full text Add to dashboard Cite

ESR and conductivity studies have been preformed on μc‐Si:H exposed to 2 MeV electron bombardment and successive annealing in order to investigate the influence of the defect density on the electronic properties of n‐type μc‐Si:H. With this approach one can vary the defect density in one and the same sample and directly deduce its influence on the electronic properties. The defect density is varied by 2 orders of magnitude with strong influence on the dark conductivity and electron spin resonance (ESR) properties. The relationship of ESR and conductivity data obtained over the whole defect density range is in agreement with the data obtained on the sets of samples deposited with different doping level. The results indicate that the Fermi level position in μc‐Si:H is defined by a balance of defect and donor states densities regardless of which of these quantities is varied. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

Section: Discussionsupporting

confidence: 80%

Section: Discussionsupporting

confidence: 80%

Variation of the Fermi level in n‐type microcrystalline silicon by electron bombardment and successive annealing: ESR and conductivity studies

Astakhov¹,

Carius²,

Petrusenko³

et al. 2010

Phys. Status Solidi (c)

View full text Add to dashboard Cite

show abstract

“…Indeed, Hall measurements have shown that the charge carrier mobility in c-Si: H depends on the charge carrier density and on the microstructure of the material. This effect is most pronounced at low carrier densities, 70,87 e.g., for a carrier density of 2 ϫ 10 16 cm −3 , the carrier mobility decreases by about a factor of 5 from I C RS Ϸ 70% to I C RS Ϸ 35%. 87 At even lower I C RS values, the mobility is further reduced, and the mobility is lowest in amorphous material.…”

Section: Conductivity In C-si: H Doped With Pmentioning

confidence: 99%

“…This effect is most pronounced at low carrier densities, 70,87 e.g., for a carrier density of 2 ϫ 10 16 cm −3 , the carrier mobility decreases by about a factor of 5 from I C RS Ϸ 70% to I C RS Ϸ 35%. 87 At even lower I C RS values, the mobility is further reduced, and the mobility is lowest in amorphous material. The strong decrease in the dark conductivity in the highly amorphous material, however, stems from the lower doping efficiency, the fairly high defect density, and the high density of band tail states which limits the concentration of mobile carriers.…”

Section: Conductivity In C-si: H Doped With Pmentioning

confidence: 99%

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

et al. 2009

View full text Add to dashboard Cite

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.

show abstract

“…The thermoelectric power measurements were done as reported previously [8]. For all measurements, a Hall bar geometry with chromium as contact material was used [9]. The thermovoltage was measured across a gap of about 6 mm defined by the evaporated chromium contacts to which thin (50 μm) thermocouples were attached.…”

mentioning

confidence: 99%

Thermopower and Hall‐effect investigations of microcrystalline silicon films

Sellmer

Bronger

Beyer

et al. 2010

Phys. Status Solidi (c)

Self Cite

View full text Add to dashboard Cite

A series of phosphorous doped microcrystalline silicon (μ c‐Si:H) and amorphous silicon (a‐Si:H) samples with different degrees of crystallinity was prepared using plasma enhanced chemical vapour deposition (PECVD). Thermoelectric power, Hall‐effect and electrical conductivity measurements were made in the temperature range 80–430 K. The crystallinity of the samples was determined by Raman measurements. The results show that the charge carrier concentration as determined by Hall‐effect and conductivity is highest and the absolute values of the thermopower are lowest at a medium magnitude (38–74%) of crystallinity.Moreover, the effective density of states at the conduction band was calculated for different temperatures by combining Hall, conductivity and thermopower measurements. At room temperature we get results close to the value for crystalline silicon by using only the crystalline amount of the microcrystalline sample and a heat of transport term of AC = 3.1. For the amorphous material, the data suggest that the Hall mobility (measured with an anomalous sign) underestimates the charge carrier mobility (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

Carrier mobilities in microcrystalline silicon films

Cited by 20 publications

References 9 publications

Variation of the Fermi level in n‐type microcrystalline silicon by electron bombardment and successive annealing: ESR and conductivity studies

Variation of the Fermi level in n‐type microcrystalline silicon by electron bombardment and successive annealing: ESR and conductivity studies

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

Thermopower and Hall‐effect investigations of microcrystalline silicon films

Contact Info

Product

Resources

About