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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

Infrared transmission spectrum for 5-10 layers of graphene on thin MCT wafer at room temperature and 77 K. The transmittance for graphene film on sapphire at room temperature is shown as a reference.
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Figure 2: Infrared transmission spectrum for 5-10 layers of graphene on thin MCT wafer at room temperature and 77 K. The transmittance for graphene film on sapphire at room temperature is shown as a reference.

Mentions: In Figure 2, we can see infrared transmission spectrum for 5-10-layer graphene film on MCT thin wafer at room temperature and 77 K. The transmission spectrum for graphene film on sapphire is also presented at room temperature as a reference. The transmission coefficient for 5-10 layers of graphene on sapphire is about 70% in the MIR regime at room temperature. This confirms further that the film consists of approximately 5-10 graphene layers. The oscillations of the transmittance for graphene films on MCT wafers are induced because the thickness of the MCT wafer (LMCT) is approximately of the radiation wavelength λ. Here the transmission coefficient of the graphene film TG is deducted from the total transmittance Tt of the air-graphene-substrate system, and the transmittance of the MCT wafer alone TMCT from Tg = Tt/TMCT. We note that such a formula holds only for a case where the thicknesses of two material layers are much larger than λ. There is no simple and analytic formula to deduct the transmittance of a thin film (L1 ≪ λ) from the total transmittance and the transmittance of the wafer (L2 ~ λ). Because, in this case, the thickness of the graphene film is much smaller than λ and LMCT ~ λ, TG may be larger than that in the oscillation regime as shown in Figure 2. When the graphene film with 5-10 alyers is placed on a thin MCT wafer, the geometric mean of the envelope curve of TG is nearly 80% in the mid-IR spectrum at room temperature and 77 K. The stronger oscillations of TG can be observed at 77 K. These results indicate that a graphene film with 5-10 graphene layers can have nearly 80% light transmittance when it is placed on top of a thin MCT wafer.


Can graphene make better HgCdTe infrared detectors?

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

Infrared transmission spectrum for 5-10 layers of graphene on thin MCT wafer at room temperature and 77 K. The transmittance for graphene film on sapphire at room temperature is shown as a reference.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Infrared transmission spectrum for 5-10 layers of graphene on thin MCT wafer at room temperature and 77 K. The transmittance for graphene film on sapphire at room temperature is shown as a reference.
Mentions: In Figure 2, we can see infrared transmission spectrum for 5-10-layer graphene film on MCT thin wafer at room temperature and 77 K. The transmission spectrum for graphene film on sapphire is also presented at room temperature as a reference. The transmission coefficient for 5-10 layers of graphene on sapphire is about 70% in the MIR regime at room temperature. This confirms further that the film consists of approximately 5-10 graphene layers. The oscillations of the transmittance for graphene films on MCT wafers are induced because the thickness of the MCT wafer (LMCT) is approximately of the radiation wavelength λ. Here the transmission coefficient of the graphene film TG is deducted from the total transmittance Tt of the air-graphene-substrate system, and the transmittance of the MCT wafer alone TMCT from Tg = Tt/TMCT. We note that such a formula holds only for a case where the thicknesses of two material layers are much larger than λ. There is no simple and analytic formula to deduct the transmittance of a thin film (L1 ≪ λ) from the total transmittance and the transmittance of the wafer (L2 ~ λ). Because, in this case, the thickness of the graphene film is much smaller than λ and LMCT ~ λ, TG may be larger than that in the oscillation regime as shown in Figure 2. When the graphene film with 5-10 alyers is placed on a thin MCT wafer, the geometric mean of the envelope curve of TG is nearly 80% in the mid-IR spectrum at room temperature and 77 K. The stronger oscillations of TG can be observed at 77 K. These results indicate that a graphene film with 5-10 graphene layers can have nearly 80% light transmittance when it is placed on top of a thin MCT wafer.

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