Radial PN junction, wire array solar cells

Kayes, Brendan M.; Filler, Michael A.; Henry, Michael David; Maiolo, James R.; Kelzenberg, Michael D.; Putnam, Morgan C.; Spurgeon, Joshua M.; Plass, Katherine E.; Scherer, Axel; Lewis, Nathan S.; Atwater, Harry A.

doi:10.1109/pvsc.2008.4922460

Cited by 22 publications

(30 citation statements)

References 72 publications

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“…While in GaAs is 14.14 %, the FF= 0.85, V OC = 935 mV, and J SC = 17.8 mA/cm 2 at 200 nm radius, and 1 µm length. It is shown that the performance difference between the planar and radial pn junction structures for GaAs is not nearly as dramatic as that for Si [6]. The simulation results for Si are in accordance with the published measured results [12].…”

Section: -1 J-v Curvessupporting

confidence: 85%

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A comparison between Si and GaAs nanowire-based photovoltaic devices

et al. 2011

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A comparison between Silicon (Si) which is an indirect band-gap semiconductor and Gallium Arsenide (GaAs) as a direct band-gap semiconductor for vertical-aligned nanowire radial pn junction-based photovoltaic (PV) devices is presented. The study takes place through determining the fill factor, the power conversion efficiency, the optimum device length and the spectrum of the quantum efficiency. The sensitivity of both Si and GaAs nanowire to temperature variations is also investigated. Finally, the array effect for nanowires of each material alone then of arrays of mixed elements' types is simulated. The results are found to be in accordance with the available experimental measurements.

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Section: -1 J-v Curvessupporting

confidence: 85%

“…The simulation in this work is based on the analytical model developed in [5,6]. The analytical solution is only possible because the carrier transport is taken to be purely radial.…”

Section: Methods Of Analysismentioning

confidence: 99%

A comparison between Si and GaAs nanowire-based photovoltaic devices

et al. 2011

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“…According to Figure 8, a silicon solar cell needs approximately 125 µm of depth to absorb 90% of the solar spectrum above its band gap (Kayes, 2008). This required thickness can be reduced in a number of different ways, including adding a rear reflector and texturing the front and back surfaces.…”

Section: Discussionmentioning

confidence: 99%

“…What this means for solar cells is that indirect band gap materials need to be thicker in order to absorb lower energy photons, such as in the infrared region. This thickness required to absorb light is called optical thickness (Bonneau, 2006;Bowden, 2008;Kayes, 2008). …”

Section: Indirect Versus Direct Band Gapmentioning

confidence: 99%

“…A typical definition is that the optical thickness is the thickness required to absorb 90% of incident light above the band gap. Using this definition, silicon has an optical thickness of approximately 125 µm (Kayes, 2008). The reason silicon is used in this study is because direct band gap materials are much more expensive and cannot be processed in the labs at Cal Poly.…”

Section: Equation 2: Light Absorptionmentioning

confidence: 99%

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Constructing and Optimizing a Single Wafer Solar Cell Array in the Microfabrication Lab at California Polytechnic State University at San Luis Obispo

Marstell¹

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This study contains research that details all aspects of how solar cells work. It also details three years' worth of studies at California Polytechnic State University (Cal Poly) that attempt to fabricate a solar cell array on a single wafer.Two tests were carried out that will help determine the optimal attributes of the solar cells. The first compared a solar cell made on a 10 µm thick silicon on insulator (SOI) wafer to solar cells made with the exact same masks on a 500 µm thick wafer. The thicker solar cell had 2.5 times the maximum power as the SOI solar cell. Aspects of the solar cell that would need to be improved are: increase thickness to between 70-100 µm from the SOI thickness, texture the front surface, add a passivation layer on the front surface, decrease the contact resistance for the metal electrodes, and add in a rear reflector. The next test was all about analyzing the metal contacts and interconnects. Page vTen gold-silver filled epoxy-gold bonds were constructed and measured ten times each, giving a grand mean between 10 and 11 Ω. Another short test was run with a commercial solar cell to characterize the change in power based on the series resistance. It was discovered that the both the epoxy and the gold add too much to the resistance. To fix this, a silver solder-like paste and a thicker contact metal should be used. There is also a derivation that details the design of a top contact layer that optimizes the finger spacing and finger width based on other solar cell factors. With the materials available at Cal Poly, a solar cell array can be fabricated on a single wafer. When accounting for the materials and processes available to the scientific community as a whole, a very effective and efficient solar cell can be fabricated.

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