Micro/nanowire-based devices have been envisioned as a promising new route toward improved electronic and optoelectronic applications, which attracts considerable research interests. However, suffering from applicable strategies to synthesize uniform core–shell structures to meet the requirement for the investigations of electrical transport behaviors along the length direction or high electron mobility transistor (HEMT) devices, heterojunction wire-based electronics have been explored limitedly. In the present work, GaN/AlN/AlGaN core–shell heterojunction microwires on patterned Si substrates were synthesized without any catalyst via metalorganic chemical vapor deposition. The as-synthesized microwires had low dislocation, sharp, and uniform heterojunction interfaces. Electrical transport performances were evaluated by fabricating HEMTs on the heterojunction microwire channels. Results demonstrated that a normally off operation was achieved with a threshold voltage of 1.4 V, a high on/off current ratio of 10⁸, a transconductance of 165 mS/mm, and a low subthreshold swing of 81 mV/dec. The normally off operation may attribute to the weak polarization along semipolar facets of the heterojunction, which leads to weak constrain of 2DEG.

中文翻译：

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a轴GaN / AlN / AlGaN核-壳异质结微线通常为高电子迁移率晶体管

基于微/纳米线的设备已经被设想为一种有前途的新途径，可以改善电子和光电子应用，这引起了相当大的研究兴趣。但是，由于受到可用于合成均匀核-壳结构以满足对沿长度方向或高电子迁移率晶体管（HEMT）器件的电传输行为进行研究的要求的策略的限制，对基于异质结线的电子设备进行了有限的研究。在目前的工作中，通过有机金属化学气相沉积法在没有任何催化剂的情况下合成了图案化Si衬底上的GaN / AlN / AlGaN核-壳异质结微线。合成后的微线具有低位错，尖锐且均匀的异质结界面。通过在异质结微丝通道上制造HEMT来评估电传输性能。结果表明，在1.4 V的阈值电压，10的高开/关电流比下实现了常关操作^{如图8所示}，跨导为165 mS / mm，低阈值摆幅为81 mV / dec。常关操作可能归因于沿着异质结半极性面的弱极化，这导致2DEG的弱约束。