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F. R. Jeffrey

Bio: F. R. Jeffrey is an academic researcher. The author has contributed to research in topics: Amorphous silicon & Silicon. The author has an hindex of 1, co-authored 1 publications receiving 5 citations.

Papers
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Journal ArticleDOI
TL;DR: Carbon grading in the buffer layer at the p/i interface increases the open circuit voltage of both p-n and n-i-p amorphous silicon solar cells.
Abstract: Carbon grading in the buffer layer at the p/i interface increases the open circuit voltage of both p-i-n and n-i-p amorphous silicon solar cells. We propose that carbon grading enlarges the electric field and reduces the electron tunneling at the p/i interface.

5 citations


Cited by
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Proceedings ArticleDOI
01 Jan 1988
TL;DR: In this paper, an extensive study of V/sub oc/ in a-Si:H p-i-n solar cells deposited by photo-CVD (chemical vapor deposition) and plasma CVD was presented.
Abstract: Results are presented of an extensive study of V/sub oc/ in a-Si:H p-i-n solar cells deposited by photo-CVD (chemical vapor deposition) and plasma-CVD. The diode parameters under illumination have been analyzed for varying p-layer and carbon graded layer thicknesses and impurity levels. It is found that the diode factor is 1.5 and that the built-in voltage is 1.05 V for most cells, indicating that the diode mechanism does not evolve from diffusion to space-charge recombination. Instead, it is concluded that in typical devices V/sub oc/ is dominated by recombination at the p/i junction. The author reviews previous analyses and conclusions of others and discusses limitations to V/sub oc/. >

7 citations

01 Jan 2002
TL;DR: In this article, a wide-gap i layer is obtained by using low substrate temperatures and sufficient hydrogendilution during the growth of the i layer to arrive at theamorphous-to-microcrystalline phase transition region.
Abstract: High-voltage wide bandgap thin-film Si n-i-p solarcells have been made using the hot-wire chemical vapordeposition (HWCVD) technique. The best open-circuitvoltage (V oc ) has exceeded 0.94 V in solar cells usingHWCVD in the entire n-i-p structure. A V oc of 0.97V hasbeen achieved using HWCVD in the n and i layers andplasma-enhanced (PE) CVD for the p layer. The highvoltages are attributed to the wide-gap i layer and animproved p/i interface. The wide-gap i layer is obtained byusing low substrate temperatures and sufficient hydrogendilution during the growth of the i layer to arrive at theamorphous-to-microcrystalline phase transition region.The optical band gap (E 04 ) of the i layer is found to be 1.90eV. These high-voltage cells also exhibit good fill factorsexceeding 0.7 with short-circuit-current densities of 8 to 10mA/cm 2 on bare stainless steel substrates. We have alsocarried out photoluminescence (PL) spectroscopy studiesand found a correlation between V

2 citations

Proceedings ArticleDOI
19 May 2002
TL;DR: In this paper, a wide-gap i layer is obtained by using low substrate temperatures and sufficient hydrogen dilution during the growth of the i layer to arrive at the amorphous-to-microcrystalline phase transition region.
Abstract: High-voltage wide bandgap thin-film Si n-i-p solar cells have been made using the hot-wire chemical vapor deposition (HWCVD) technique. The best open-circuit voltage (V/sub oc/) has exceeded 0.94 V in solar cells using HWCVD in the entire n-i-p structure. A V/sub oc/ of 0.97 V has been achieved using HWCVD in the n and i layers and plasma-enhanced (PE) CVD for the p layer. The high voltages are attributed to the wide-gap i layer and an improved p/i interface. The wide-gap i layer is obtained by using low substrate temperatures and sufficient hydrogen dilution during the growth of the i layer to arrive at the amorphous-to-microcrystalline phase transition region. The optical band gap (E/sub o4/) of the i layer is found to be 1.90 eV. These high-voltage cells also exhibit good fill factors exceeding 0.7 with short-circuit-current densities of 8 to 10 mA/cm/sup 2/ on bare stainless steel substrates. We have also carried out photoluminescence (PL) spectroscopy studies and found a correlation between V/sub oc/ and the PL peak energy position.

2 citations

Book ChapterDOI
01 Jan 1995
TL;DR: In this paper, the optoelectronic properties of amorphous silicon using the plasma-enhanced chemical vapor deposition (PECVD) technique have been studied and an interdependence exists among crucial deposition parameters and their influence on the material properties and hence on the performance of the electronic devices.
Abstract: Publisher Summary The aim of this chapter is to study optoelectronic properties of amorphous silicon using the plasma-enhanced chemical vapor deposition (PECVD) technique. The most intensively studied of the amorphous semiconductor family is amorphous silicon (a-Si), and particularly the hydrogenated variety. Any deposition technique that does not employ a reactive environment of H (or F) leads to extremely poor materials in terms of high density of localized states (DOS) due to Si dangling bonds, such that the films cannot be electronically doped, which then precludes any electronic device possibilities. Numerous techniques for depositing a-Si-based alloys have been attempted, plasma-enhanced chemical vapor deposition (PECVD) in SiH4 gas, PECVD in SiF4 and H2 gas mixtures, reactive sputtering of Si in H environments, evaporation of Si in the presence of H, CVD of SiH4 gas and higher silanes, photo-CVD, electron cyclotron resonance (ECR) PECVD, and remote PECVD. This chapter attempts to show that an interdependence exists among crucial deposition parameters and their influence on the material properties and hence on the performance of the electronic devices. Amorphous silicon technology has now matured to the point where many products are now commercially available.

2 citations

01 May 2002
TL;DR: In this paper, a wide-gap i layer is obtained by using low substrate temperatures and sufficient hydrogen dilution during the growth of the i layer to arrive at the amorphous-to-microcrystalline phase transition region.
Abstract: High-voltage wide bandgap thin-film Si n-i-p solar cells have been made using the hot-wire chemical vapor deposition (HWCVD) technique. The best open-circuit voltage (Voc) has exceeded 0.94 V in solar cells using HWCVD in the entire n-i-p structure. A Voc of 0.97V has been achieved using HWCVD in the n and i layers and plasma-enhanced (PE) CVD for the p layer. The high voltages are attributed to the wide-gap i layer and an improved p/i interface. The wide-gap i layer is obtained by using low substrate temperatures and sufficient hydrogen dilution during the growth of the i layer to arrive at the amorphous-to-microcrystalline phase transition region. The optical band gap (E04) of the i layer is found to be 1.90 eV. These high-voltage cells also exhibit good fill factors exceeding 0.7 with short-circuit-current densities of 8 to 10 mA/cm2 on bare stainless steel substrates. We have also carried out photoluminescence (PL) spectroscopy studies and found a correlation between Voc and the PL peak energy position.