Zero-field thermopower of a thin heterostructure membrane with a two-dimensional electron gas
Zero-field thermopower of a thin heterostructure membrane with a two-dimensional electron gas
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二维电子气异质结构薄膜的零场热电势
DOI：
10.1103/physrevb.85.075408
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发表时间：
2011
影响因子：
3.7
通讯作者：
W. Hansen
中科院分区：
文献类型：
--
作者：
M. Schmidt;G. Schneider;C. Heyn;A. Stemmann;W. Hansen
我们研究包含二维电子系统的微米级独立膜的低温热电势。厚度为 320 nm 的悬浮膜，包括 $34\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{m}$ 霍尔棒几何形状中的高电子迁移率结构，由分子束外延生长的 GaAs/AlGaAs 异质结构制备。膜中心区域的焦耳加热产生相对于膜附着到冷储器的悬浮点的热梯度。由于导热系数低，膜上的温度测量显示出很强的热梯度。我们测量了零场热电势，发现声子阻力的贡献在高达 7 K 的低温下受到抑制。
We study the low-temperature thermopower of micrometer-sized free-standing membranes containing a two-dimensional electron system. Suspended membranes of 320 nm thickness, including a high-electron-mobility structure in the Hall bar geometry of $34\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{m}$ 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.