The structural, optical, and electrical properties of vacuum evaporated Cu-doped ZnTe polycrystalline thin films

Feng, Li; Mao, D.; Tang, Jinkui; Collins, R. T.; Trefny, J. U.

doi:10.1007/bf02655377

Cited by 35 publications

(19 citation statements)

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“…The material of the back contact for CdTe has been investigated and applied, such as ZnTe, ZnTe/ZnTe:Cu. [3][4][5] Copper(Cu) has been found to be an acceptor dopant for CdTe film and is widely used in high-efficiency CdTe solar cells.…”

Section: Introductionmentioning

confidence: 99%

Study of CuxTe Polycrystalline Thin Films for CdTe Solar Cells

Song

Zheng

2010

2010 Asia-Pacific Power and Energy Engineering Conference

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Section: Introductionmentioning

confidence: 99%

Study of CuxTe Polycrystalline Thin Films for CdTe Solar Cells

Song

Zheng

2010

2010 Asia-Pacific Power and Energy Engineering Conference

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“…Thus, stress which is believed to be the major cause of nanorods origin is excluded. Similarly, no cracks were observed since the films were of good crystallinity, so in our case intrinsic stress did not play a significant role, contrary to other evaporation methods [14].…”

Section: Surface Morphologymentioning

confidence: 44%

“…The history of Bi nanorods fabrication is dated 20 years ago [14]. The first such structures had a diameter in the range of microns while in the later ones, a diameter of 200 nm was achieved by high pressure casting.…”

Section: Introductionmentioning

confidence: 99%

Catalyst free growth of single-crystalline bismuth nanorods by closed space sublimation technique

Usman

Maqsood

2015

Materials Science-Poland

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In the present study, bismuth (Bi) thin films having thickness of 335 nm have been deposited onto a glass substrate by closed space sublimation (CSS) technique. Besides this, spontaneous growth of Bi nanorods has also been investigated for the first time, without template and catalyst assistance in a substrate temperature range of 380 to 430°C using CSS technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate microstructure, morphology and roughness of the Bi nanorods. The diameter and length ranges of Bi nanorods were 80 to 400 nm and 3 to 5 µm, respectively. Moreover, they exhibited a rhombohedral structure with a dominant peak indexed at (012), (104), and (110). The mass percentage of Bi, determined by energy dispersive X-ray (EDX), was 99.93 %. The studies of electrical resistivity, Hall coefficient, magnetoresistivity, hole mobility and carrier concentration of Bi thin films were performed at 300 to 350 K and the electrical properties were found to be a function of temperature. The basic aim was to investigate the spectacular evolution of Bi nanostructures on as-deposited thin films and effects of thickness on their structural, electrical and dielectric properties. Detailed examination of SEM micrographs eliminated all other growth modes except self-catalytic tip growth by Vapor-Solid (VS) growth process which is believed to provide the driving force for spontaneous nanorod growth at high substrate temperature. Deposition of thinner Bi films provided a new possibility for fabrication of Bi nanorods of high quality.

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“…The series resistance obtained from cells with a ZnTe layer is less than 0.1 Q cm 2 , much smaller than that obtained without a ZnTe layer. Because the doping concentration of ZnTe is over 10 2 0 cm-3 [19], the contact between the final metal contact and ZnTe is not expected to depend critically on the work function of the metals. Indeed, the lowest series resistances we obtained with Ni-, Au-and Co-contacted cells are very similar.…”

Section: Optimization Of the Znte:cu Layer And Its Processing Conditionsmentioning

confidence: 99%

“…We have also investigated higher annealing temperatures. However, cells with good efficiencies were only obtainable at annealing temperatures below 200°C, even though ZnTe films with improved electrical and structural properties can be obtained at higher annealing temperatures [19]. This is possibly caused by degradation of the CdTe/CdS junction or reactions between CdTe and ZnTe at high annealing temperatures.…”

mentioning

confidence: 99%

Polycrystalline thin film cadmium telluride solar cells fabricated by electrodeposition. Annual technical report, 20 March 1995--19 March 1996

Trefny¹,

Mao

1997

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Executive Summary ObjectivesThe objective of this project is to develop improved processes for the fabrication of CdTe/CdS polycrystalline thin fllm solar cells.The technique we use. for the formation of CdTe, electrodeposition, is a non-vacuum, low-cost technique that is attractive for economic, large-scale production. Technical ApproachDuring the past year, our research and development efforts have focused on several steps that are most critical to the fabrication of high-efficiency CdTe solar cells. These include the optimization of CdTe electrodeposition process, the effect of pre-treatment of CdS substrates, the post-deposition annealing of CdTe, and back contact formation using Cu-doped ZnTe. Systematic investigations of these processing steps have lead to better understanding and improved device performances of the CdTe-based solar cells. ResultsStudies of the �rowth and properties ofCBD CdS tbjo films. The structural properties of the fllms and the growth mechanisms were studied by investigating CdS samples prepared at different deposition times. A duplex structure with an inner compact layer and an outer porous layer and three growth stages is consistent with our data. The measurement of refractive index as a function of deposition time provides a simple way to determine the transition point from compact layer growth to porous layer growth, which is important for the optimization of CdS growth conditions in photovoltaic applications. Careful XRD analyses allowed unambiguous determination of crystal properties.Effe ctofCdCl, treatmentofCdS films. We-investigated the effect of CdCl2 treatment of CdS films on the photovoltaic performance of CdTe solar cells. X -ray diffraction studies indicated that the diffusion of S into CdTe is qualitatively the same for CdTe/CdS films fabricated with both as deposited and CdCl2-treated CdS. A major difference was observed in the extent of Te diffusion into CdS for the two types of CdS films. Full conversion of CdS into CdS 1.yTey was observed for films prepared with as-deposited CdS, while the fo rmation of the ternary phase was below the detection limit for films prepared with CdCl2-treated CdS. Photoluminescence measurements confirmed this result. The difference in interdiffusion leads to differences in optical transmission of CdS films and spectral response of CdTe/CdS solar cells. An increase of 2.7 mA/cm 2 in short-circuit current density was observed as a result of improved spectral response in the wavelength range of 500-600 nm for the CdCl2-treated CdS. Optimization of CdTe and CdS film thicknesses. We have investigated the effect of CdTe and CdS thickness on the photovoltaic performance of the resulting cells. We found that an increase in the CdTe thickness from 2 J.lm to 3 . 5 J.lm lead to a consistent improvement in V oc by 40-60 m V. The shunt resistance of the cells was also increased. As a result, V oc greater than 800 m V and Rsh greater than 1000 n cm2 were regularly obtained. SEM measurements indicated that the average CdTe grain size after CdCb treatm...

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The structural, optical, and electrical properties of vacuum evaporated Cu-doped ZnTe polycrystalline thin films

Cited by 35 publications

References 11 publications

Study of CuxTe Polycrystalline Thin Films for CdTe Solar Cells

Study of CuxTe Polycrystalline Thin Films for CdTe Solar Cells

Catalyst free growth of single-crystalline bismuth nanorods by closed space sublimation technique

Polycrystalline thin film cadmium telluride solar cells fabricated by electrodeposition. Annual technical report, 20 March 1995--19 March 1996

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