New diagnostic aspects of high rate a-Si:H deposition in a VHF plasma

Heintze, M.; Zedlitz, R.

doi:10.1016/0022-3093(96)00035-x

Cited by 42 publications

(29 citation statements)

References 7 publications

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“…Heintze and Zedlitz have shown that ion energy in plasmas decreases with increasing frequency up to at least 180 MHz. 13 For high plasma excitation frequencies plasma resistance and sheath width is decreased. Therefore voltage needed to maintain the plasma is reduced which also leads to lower plasma potentials.…”

mentioning

confidence: 99%

Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

Łupina

Strobel

Dąbrowski

et al. 2016

Applied Physics Letters

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Plasma-enhanced chemical vapor deposition of thin a-Si:H layers on transferred large area graphene is investigated. Radio frequency (RF, 13.56 MHz) and very high frequency (VHF, 140 MHz) plasma processes are compared. Both methods provide conformal coating of graphene with Si layers as thin as 20 nm without any additional seed layer. The RF plasma process results in amorphization of the graphene layer. In contrast, the VHF process keeps the high crystalline quality of the graphene layer almost intact. Correlation analysis of Raman 2D and G band positions indicates that Si deposition induces reduction of the initial doping in graphene and an increase of compressive strain. Upon rapid thermal annealing the amorphous Si layer undergoes dehydrogenation and transformation into a polycrystalline film whereby a high crystalline quality of graphene is preserved.Ability to deposit uniform thin layers of insulators and semiconductors on graphene is of crucial importance for many envisioned applications of this material in advanced electronic and photonic devices.1 Si-graphene junctions are particularly interesting for graphene-based photodetectors, sensors, and high-frequency vertical heterojunction transistors.

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mentioning

confidence: 99%

Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

Łupina

Strobel

Dąbrowski

et al. 2016

Applied Physics Letters

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“…Heintze et al (Heintze et al, 1993;Heintze and Zedlitz, 1996) have measured an enhanced ion flux on the growth surface at higher frequencies (see Fig. 6) which is related to the changes in both the bulk plasma and in the sheath.…”

Section: Vhf-gd Deposition Techniquementioning

confidence: 93%

“…Energy distribution of ions impinging on the substrate in a silane/hydrogen plasma for different plasma excitation frequencies, for a capacitively-coupled glow discharge plasma of pure silane. Data taken from Heintze and Zedlitz (1996). …”

Section: Vhf-gd Deposition Techniquementioning

confidence: 99%

Amorphous solar cells, the micromorph concept and the role of VHF-GD deposition technique

Meier¹,

Kroll²,

Vallat-Sauvain³

et al. 2004

Solar Energy

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During the last two decades, the Institute of Microtechnology (IMT) has contributed in two important fields to future thin-film silicon solar cell processing and design:(1) In 1987, IMT introduced the so-called ''very high frequency glow discharge (VHF-GD)'' technique, a method that leads to a considerable enhancement in the deposition rate of amorphous and microcrystalline silicon layers. As a direct consequence of reduced plasma impedances at higher plasma excitation frequencies, silane dissociation is enhanced and the maximum energy of ions bombarding the growing surface is reduced. Due to softer ion bombardment on the growing surface, the VHF process also favours the formation of microcrystalline silicon. Based on these beneficial properties of VHF plasmas, for the growth of thin silicon films, plasma excitation frequencies f exc in the range 30-300 MHz, i.e. clearly higher than the standard 13.56 MHz, are indeed scheduled to play an important role in future production equipment.(2) In 1994, IMT pioneered a novel thin-film solar cell, the microcrystalline silicon solar cell. This new type of thinfilm absorber material--a form of crystalline silicon--opens up the way for a new concept, the so-called ''micromorph'' tandem solar cell concept. This term stands for the combination of a microcrystalline silicon bottom cell and an amorphous silicon top cell. Thanks to the lower band gap and to the stability of microcrystalline silicon solar cells, a better use of the full solar spectrum is possible, leading, thereby, to higher efficiencies than those obtained with solar cells based solely on amorphous silicon.Both the VHF-GD deposition technique and the ''micromorph'' tandem solar cell concept are considered to be essential for future thin-film PV modules, as they bear the potential for combining high-efficiency devices with low-cost manufacturing processes.

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“…2a). As already mentioned in the past, one of the reasons for this may be the fact that at higher frequencies, the average energy of ions involved in ion bombardment of the growing layer is reduced [10].…”

Section: Plasma Excitation Frequencymentioning

confidence: 95%

More stable low gap a-Si:H layers deposited by PE-CVD at moderately high temperature with hydrogen dilution

Ziegler

Daudrix

Droz

et al. 2001

Solar Energy Materials and Solar Cells

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In the present work, several series with variation of deposition parameters such as hydrogen dilution ratio, VHF-power and plasma excitation frequency f have been extensively analyzed. Compared with`conventionala more-stable layers obtained at 200}2503C and high H dilution ratios of about 10, it was observed that electrical transport properties after light-induced degradation of layers deposited at`moderately higha temperatures (300}3503C) are equivalent but required lower H dilution ratios (between 2 and 4). As a consequence, the deposition rate of more stable layers obtained at moderately high temperatures is increased by a factor of 2. Moreover, optical gaps of a-Si:H deposited at 300}3503C are signi"cantly lower (by approx. 10 meV); furthermore, they decrease with f .

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New diagnostic aspects of high rate a-Si:H deposition in a VHF plasma

Cited by 42 publications

References 7 publications

Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

Amorphous solar cells, the micromorph concept and the role of VHF-GD deposition technique

More stable low gap a-Si:H layers deposited by PE-CVD at moderately high temperature with hydrogen dilution

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