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Can graphene make better HgCdTe infrared detectors?

Xu W, Gong Y, Liu L, Qin H, Shi Y - Nanoscale Res Lett (2011)

Bottom Line: We develop a simple and low-cost technique based on chemical vapor deposition from which large-size graphene films with 5-10 graphene layers can be produced reliably and the graphene films can be transferred easily onto HgCdTe (MCT) thin wafers at room temperature.It is found that the averaged light transmittance of the graphene film on MCT thin wafer is about 80% in the mid-infrared bandwidth at room temperature and 77 K.Moreover, we find that the electrical conductance of the graphene film on the MCT substrate is about 25 times larger than that of the MCT substrate at room temperature and 77 K.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Yunnan University, Kunming 650091, China. wenxu_issp@yahoo.cn.

ABSTRACT
We develop a simple and low-cost technique based on chemical vapor deposition from which large-size graphene films with 5-10 graphene layers can be produced reliably and the graphene films can be transferred easily onto HgCdTe (MCT) thin wafers at room temperature. The proposed technique does not cause any thermal and mechanical damages to the MCT wafers. It is found that the averaged light transmittance of the graphene film on MCT thin wafer is about 80% in the mid-infrared bandwidth at room temperature and 77 K. Moreover, we find that the electrical conductance of the graphene film on the MCT substrate is about 25 times larger than that of the MCT substrate at room temperature and 77 K. These experimental findings suggest that, from a physics point of view, graphene can be utilized as transparent electrodes as a replacement for metal electrodes while producing better and cheaper MCT infrared detectors.

No MeSH data available.


Related in: MedlinePlus

TEM image of the graphene film grown by the CVD technique. The inset is the SAED pattern of the graphene film.
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Figure 1: TEM image of the graphene film grown by the CVD technique. The inset is the SAED pattern of the graphene film.

Mentions: In this study, the graphene films are grown using the standard chemical vapor deposition (CVD) technique. CH4 is taken as carbon precursor flowing over a 500-nm-thick Ni film catalyst on a SiO2 substrate. The reaction temperature is 900°C, and the flow rates of CH4 and H2 are about 50 and 150 sccm, respectively. The reaction time is around 5 min. In this way, we can produce reliably the large-size and high-quality graphene films with a fewer layers (5-10) of graphene. This is verified by the measurements of optical transmittance and transmission electron microscopy (TEM). Figure 1 shows the low-resolution TEM image and the SAED pattern of the graphene film, wherein we can see that a highly crystallized structure of few-layer graphene film has been achieved with the typical sixfold symmetry. Using this technique, the size of the graphene film produced is mainly determined by the size of the Ni film which plays a role as catalyst. The graphene layer on Ni film is then transferred onto the thin MCT wafers at room temperature through (i) spin casting with PMMA at 3000 rpm/min for 1 min; (ii) baking at 170°C for 2 h; (iii) peeling off graphene on Ni film by etching in 1 mol/l NaOH at 80°C, followed by etching underlying Ni film by FeCl3 solution; and (iv) transferring the graphene film onto MCT wafer in water at room temperature. In addition to the large size of the graphene film that can be transferred onto the MCT wafer, another advantage of this technique is that there is not at all a thermal or mechanical damage to the MCT wafer samples. We know that Hg in MCT evaporates at about 180°C. Thus, the conventional method used for growing graphene film on substrate, such as MBE growth and thermal expansion, cannot be used for growing graphene directly on the MCT substrates. The MCT wafers used in this investigation are with the approximate thicknesses of 1 μm and the sizes of 1 cm2. The MCT wafers are placed on sapphire substrate.


Can graphene make better HgCdTe infrared detectors?

Xu W, Gong Y, Liu L, Qin H, Shi Y - Nanoscale Res Lett (2011)

TEM image of the graphene film grown by the CVD technique. The inset is the SAED pattern of the graphene film.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211312&req=5

Figure 1: TEM image of the graphene film grown by the CVD technique. The inset is the SAED pattern of the graphene film.
Mentions: In this study, the graphene films are grown using the standard chemical vapor deposition (CVD) technique. CH4 is taken as carbon precursor flowing over a 500-nm-thick Ni film catalyst on a SiO2 substrate. The reaction temperature is 900°C, and the flow rates of CH4 and H2 are about 50 and 150 sccm, respectively. The reaction time is around 5 min. In this way, we can produce reliably the large-size and high-quality graphene films with a fewer layers (5-10) of graphene. This is verified by the measurements of optical transmittance and transmission electron microscopy (TEM). Figure 1 shows the low-resolution TEM image and the SAED pattern of the graphene film, wherein we can see that a highly crystallized structure of few-layer graphene film has been achieved with the typical sixfold symmetry. Using this technique, the size of the graphene film produced is mainly determined by the size of the Ni film which plays a role as catalyst. The graphene layer on Ni film is then transferred onto the thin MCT wafers at room temperature through (i) spin casting with PMMA at 3000 rpm/min for 1 min; (ii) baking at 170°C for 2 h; (iii) peeling off graphene on Ni film by etching in 1 mol/l NaOH at 80°C, followed by etching underlying Ni film by FeCl3 solution; and (iv) transferring the graphene film onto MCT wafer in water at room temperature. In addition to the large size of the graphene film that can be transferred onto the MCT wafer, another advantage of this technique is that there is not at all a thermal or mechanical damage to the MCT wafer samples. We know that Hg in MCT evaporates at about 180°C. Thus, the conventional method used for growing graphene film on substrate, such as MBE growth and thermal expansion, cannot be used for growing graphene directly on the MCT substrates. The MCT wafers used in this investigation are with the approximate thicknesses of 1 μm and the sizes of 1 cm2. The MCT wafers are placed on sapphire substrate.

Bottom Line: We develop a simple and low-cost technique based on chemical vapor deposition from which large-size graphene films with 5-10 graphene layers can be produced reliably and the graphene films can be transferred easily onto HgCdTe (MCT) thin wafers at room temperature.It is found that the averaged light transmittance of the graphene film on MCT thin wafer is about 80% in the mid-infrared bandwidth at room temperature and 77 K.Moreover, we find that the electrical conductance of the graphene film on the MCT substrate is about 25 times larger than that of the MCT substrate at room temperature and 77 K.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Yunnan University, Kunming 650091, China. wenxu_issp@yahoo.cn.

ABSTRACT
We develop a simple and low-cost technique based on chemical vapor deposition from which large-size graphene films with 5-10 graphene layers can be produced reliably and the graphene films can be transferred easily onto HgCdTe (MCT) thin wafers at room temperature. The proposed technique does not cause any thermal and mechanical damages to the MCT wafers. It is found that the averaged light transmittance of the graphene film on MCT thin wafer is about 80% in the mid-infrared bandwidth at room temperature and 77 K. Moreover, we find that the electrical conductance of the graphene film on the MCT substrate is about 25 times larger than that of the MCT substrate at room temperature and 77 K. These experimental findings suggest that, from a physics point of view, graphene can be utilized as transparent electrodes as a replacement for metal electrodes while producing better and cheaper MCT infrared detectors.

No MeSH data available.


Related in: MedlinePlus