High Photoresponsivity and Short Photoresponse Times in Few-Layered WSe2 Transistors

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• 作者：Nihar R. Pradhan ; Jonathan Ludwig ; Zhengguang Lu ; Daniel Rhodes ; Michael M. Bishop ; Komalavalli Thirunavukkuarasu ; Stephen A. McGill ; Dmitry Smirnov ; Luis Balicas
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：June 10, 2015
• 年：2015
• 卷：7
• 期：22
• 页码：12080-12088
• 全文大小：514K
• ISSN：1944-8252

文摘

Here, we report the photoconducting response of field-effect transistors based on three atomic layers of chemical vapor transport grown WSe₂ crystals mechanically exfoliated onto SiO₂. We find that trilayered WSe₂ field-effect transistors, built with the simplest possible architecture, can display high hole mobilities ranging from 350 cm²/(V s) at room temperature (saturating at a value of 鈭?00 cm²/(V s) below 50 K) displaying a strong photocurrent response, which leads to exceptionally high photoresponsivities up to 7 A/W under white light illumination of the entire channel for power densities p < 10² W/m². Under a fixed wavelength of 位 = 532 nm and a laser spot size smaller than the conducting channel area, we extract photoresponsitivities approaching 100 mA/W with concomitantly high external quantum efficiencies up to 鈭?0% at room temperature. These values surpass values recently reported from more complex architectures, such as graphene and transition metal dichalcogenides based heterostructures. Also, trilayered WSe₂ phototransistors display photoresponse times on the order of 10 渭s. Our results indicate that the addition of a few atomic layers considerably decreases the photoresponse times, probably by minimizing the interaction with the substrates, while maintaining a very high photoresponsivity.