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arXiv 1111.1324cond-mat.mes-hall
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含二维电子气异质结构薄膜的零场热电势

Zero-field thermopower of a thin heterostructure membrane with a 2D electron gas

M. Schmidt, G. Schneider, Ch. Heyn, A. Stemmann, W. Hansen

摘要:

我们研究了含有二维电子系统的微米级独立膜的低温热电势。用分子束外延技术生长GaAs/AlGaAs异质结,制备了320 nm厚的悬浮膜,其中包括34 μ m长的高电子迁移率霍尔栅结构。在膜的中心区域上的焦耳加热相对于膜附接到冷储器的悬挂点产生热梯度。对膜的温度测量揭示了由于低热导率而导致的强热梯度。我们测量了零场热电势,发现声子拖曳的贡献在低温下被抑制到7 K。

英文摘要:

We study the low-temperature thermopower of micron sized, free-standing membranes containing a two-dimensional electron system. Suspended membranes of 320 nm thickness including a high electron mobility structure in Hall bar geometry of 34 μm length are prepared from GaAs/AlGaAs heterostructures grown by molecular beam epitaxy. Joule heating on the central region of the membrane generates a thermal gradient with respect to the suspension points where the membrane is attached to cold reservoirs. Temperature measurements on the membrane reveal strong thermal gradients due to the low thermal conductivity. We measure the zero-field thermopower and find that the phonon-drag contribution is suppressed at low temperatures up to 7 K.

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