Low-temperature characterization and micropatterning of coevaporated Bi2Te3 and Sb2Te3 films
Low-temperature characterization and micropatterning of coevaporated Bi2Te3 and Sb2Te3 films
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DOI：
10.1063/1.3033381
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发表时间：
2008-12-01
影响因子：
3.2
通讯作者：
Kaviany, Massoud
中科院分区：
文献类型：
--
作者：
Huang, Baoling;Lawrence, Chris;Kaviany, Massoud
共蒸发 Bi2Te3 和 Sb2Te3 薄膜的热电 (TE) 特性在 100 至 300 K 范围内测量塞贝克系数 alpha(S)，在 5 至 300 K 范围内测量电阻率 rho(e)、迁移率 mu(e) 和霍尔系数 R-H。对于TE薄膜的低温表征，还研究了Bi、Te和Sb共蒸发沉积形成Bi2Te3和Sb2Te3薄膜的条件，包括基底材料、基底温度T-sub和元素通量比(FR)。 Te 在 473 K 以上发生的再升华显着影响薄膜的成分和质量。 Bi2Te3 薄膜的最佳沉积条件是 T-sub= 533 K 和 FR= 2.4，Sb2Te3 薄膜的最佳沉积条件是 T-sub= 503 K 和 FR= 3.0。两种薄膜的 TE 性能都强烈依赖于温度，而 Bi2Te3 薄膜由于不同的主要散射机制而表现出比 Sb2Te3 薄膜更强的温度依赖性。两种共蒸发薄膜的 alpha(S) 都接近或高于块体材料，但 rho(e) 更高（由于 Sb2Te3 薄膜的载流子浓度较低，Bi2Te3 薄膜的 mu(e) 较低）。此外，Bi2Te3 和 Sb2Te3 薄膜在低温下没有发现冻析机制。 Bi2Te3 和 Sb2Te3 薄膜的室温功率因数 alpha(2)(S)/rho(e) 分别为 2.3 和 2.0 mW/K-2 m，Bi2Te3 在 T= 220 K 时的最大值为 2.7 mW/K-2 m，Sb2Te3 在 T= 280 K 时的最大值为 2.1 mW/K-2 m。 TE 薄膜的微图案（20μm），性能没有显着变化。 (C) 2008 年美国物理研究所。 [DOI：10.1063/1.3033381]
Thermoelectric (TE) properties of the coevaporated Bi2Te3 and Sb2Te3 films are measured from 100 to 300 K for Seebeck coefficient alpha(S) and from 5 to 300 K for electrical resistivity rho(e), mobility mu(e), and Hall coefficient R-H. For the low-temperature characterization of TE films, the conditions for coevaporation deposition of Bi, Te, and Sb to form Bi2Te3 and Sb2Te3 films are also investigated, including substrate material, substrate temperature T-sub, and elemental flux ratio (FR). The resublimation of Te occurring above 473 K significantly affects the film composition and quality. Our optimal deposition conditions for Bi2Te3 films are T-sub= 533 K and FR= 2.4, and those for Sb2Te3 films are T-sub= 503 K and FR= 3.0. The TE properties of both films are strongly temperature dependent, while Bi2Te3 films show a stronger temperature dependence than Sb2Te3 films due to different major scattering mechanisms. alpha(S) of both the coevaporated films are close to or higher than those of bulk materials, but rho(e) is much higher (due to lower carrier concentrations for Sb2Te3 films and lower mu(e) for Bi2Te3 films). Also, no freeze-out regime is found for both Bi2Te3 and Sb2Te3 films at low temperatures. The room-temperature power factors of alpha(2)(S)/rho(e) for Bi2Te3 and Sb2Te3 films are 2.3 and 2.0 mW/K-2 m, and the maxima are 2.7 mW/K-2 m for Bi2Te3 at T= 220 K and 2.1 mW/K-2 m for Sb2Te3 at T= 280 K. Shadow mask technique is successfully used for the micropatterning (20 mu m) of TE films with no significant change in properties. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3033381]