On the roughness of hydrogen-plasma treated diamond (100) surfaces

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• 作者：Koslowski ; B. ; Strobel ; S. ; Wenig ; M.J. ; Martschat ; R. ; Ziemann ; P.
• 关键词：Diamond(100) ; Roughness ; Etching ; STM ; AFM ; Hydrogen ; Plasma
• 刊名：Diamond and Related Materials
• 出版年：1998
• 出版时间：February, 1998
• 年：1998
• 卷：7
• 期：2-5
• 页码：322-326
• 全文大小：509 K

文摘

To investigate the possibility of influencing the roughness of diamond(100) surfaces, type Ib or heavily boron (B)-doped HPHT diamond crystals were mechanically and chemo-mechanically polished, and additionally exposed to a microwave-assisted hydrogen plasma. The resulting roughness and surface topology was analyzed on a macroscopic scale by stylus profilometry (PFM), and on microscopic scales by STM and AFM. The following results have been observed: the surface roughness (rms-value) is reduced by mechanical polishing from 4 nm_rms (as received) to about 2 nm_rms (PFM). This step, however, leads to scratches with depths up to 40 nm_pp. Chemo-mechanical polishing with KNO₃ reduces the surface roughness further to typically 100 pm_rms (PFM), usually eliminating the above scratches. The roughness determined by STM is typically 5-10-times higher than measured by PFM. After exposing B-doped samples for 3 min to the H-plasma under typical CVD growth conditions, the roughness increases up to 4 nm_rms and a “brick-wall” pattern appears formed by weak cusps running along [110]. After exposure for an additional 5 min, the surface roughness of the B-doped samples increases further to 20-40 nm_rms and exhibits a regular pattern frequently with characteristic structures of 60 nm width, 250 nm length, and 160 nm height running along approximately [110]. The “roofs” are faceted with faces of approximately {XX1}. These results will be discussed in terms of strain relaxation, similar to the surface roughening observed on SiGe/Si and anisotropic etching of defects.