Anomalous temperature dependence of absorption edge in narrow-gap HgCdTe semiconductors
Anomalous temperature dependence of absorption edge in narrow-gap HgCdTe semiconductors
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DOI：
10.1063/1.2221411
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发表时间：
2006-07
影响因子：
4
通讯作者：
F. Yue;J. Shao;Xiang Lü;Wei Huang;J. Chu;Jun Wu;Xingchao Lin;Li He
中科院分区：
文献类型：
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作者：
F. Yue;J. Shao;Xiang Lü;Wei Huang;J. Chu;Jun Wu;Xingchao Lin;Li He
报道了窄禁带Hg1−xCdxTe半导体在低温下吸收边随温度的反常变化。在11-300K温度范围内，分别测量了体外延和分子束外延Hg1-−_xCd_xTe的红外吸收光谱。结果表明，在30-70K温度范围内，吸收边发生了反常位移。分析表明：(1)这种现象是由样品中的汞空位引起的，其能级位于Hg1-−_xCd_xTe价带上方约9-12 meV；(2)传统的确定带隙能量的判据，如由吸收光谱确定禁带能，只要有汞空位存在，特别是在77K以上的温度下，就不够准确。从而解释了为什么探测器的截止波长和构成探测器的材料的吸收边波长之间应该存在差异。
Abnormal temperature dependence of absorption edge is reported for narrow-gap Hg1−xCdxTe semiconductors at low temperature. Infrared absorption spectra are taken for bulk and molecular-beam epitaxial Hg1−xCdxTe, respectively, in the temperature range of 11–300K. The results indicate an abnormal shift of the absorption edge around the temperature range of 30–70K. Analysis suggests that (i) the phenomenon is introduced by Hg vacancies in the samples, of which the energy level locates about 9–12meV above the Hg1−xCdxTe valence band, and (ii) the conventional criterion for the determination of band gap energy, Eg, from absorption spectra is not accurate enough as soon as Hg vacancies exist, especially at a temperature above 77K. It hence provides an explanation why there should exist difference between the cutoff wavelength of the detector and the absorption-edge (Eg) wavelength of the material the detector was made of.