Greco Giuseppe, Giannazzo Filippo, Frazzetto Alessia, Raineri Vito, Roccaforte Fabrizio
Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII n, 5, Zona Industriale, 95121 Catania, Italy.
Nanoscale Res Lett. 2011 Feb 11;6(1):132. doi: 10.1186/1556-276X-6-132.
The effects of near-surface processing on the properties of AlGaN/GaN heterostructures were studied, combining conventional electrical characterization on high-electron mobility transistors (HEMTs), with advanced characterization techniques with nanometer scale resolution, i.e., transmission electron microscopy, atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM). In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values. Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer. By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.
研究了近表面处理对AlGaN/GaN异质结构特性的影响，将高电子迁移率晶体管（HEMT）上的传统电学表征与具有纳米级分辨率的先进表征技术相结合，即透射电子显微镜、原子力显微镜（AFM）和导电原子力显微镜（C-AFM）。特别是，栅极区域基于CHF3的等离子体工艺导致HEMT器件中的阈值电压向负值减小的方向移动。通过C-AFM在样品表面获取的二维电流图使我们能够监测材料中掺入的等离子体氟引起的局部电学变化。将结果与最近引入的栅极控制工艺进行了比较：AlGaN层的局部快速热氧化工艺。通过该工艺，可以可靠地在AlGaN表面引入可控的薄氧化层，同时其下方层的电阻会局部增加。
