Lucovsky, Gerald and Phillips, James C. (2010) Nano-regime Length Scales Extracted from the First Sharp Diffraction Peak in Non-crystalline SiO2 and Related Materials: Device Applications. NANOSCALE RESEARCH LETTERS, 5 (3). pp. 550-558. ISSN 1931-7573 (Print) 1556-276X (Online)
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This paper distinguishes between two different scales of medium range order, MRO, in non-crystalline SiO2: (1) the first is ~0.4 to 0.5Â nm and is obtained from the position of the first sharp diffraction peak, FSDP, in the X-ray diffraction structure factor, S(Q), and (2) the second is ~1Â nm and is calculated from the FSDP full-width-at-half-maximum FWHM. Many-electron calculations yield SiâO third- and OâO fourth-nearest-neighbor bonding distances in the same 0.4â0.5Â nm MRO regime. These derive from the availability of empty Si dÏ orbitals for back-donation from occupied O pÏ orbitals yielding narrow symmetry determined distributions of third neighbor SiâO, and fourth neighbor OâO distances. These are segments of six member rings contributing to connected six-member rings with ~1Â nm length scale within the MRO regime. The unique properties of non-crystalline SiO2 are explained by the encapsulation of six-member ring clusters by five- and seven-member rings on average in a compliant hard-soft nano-scaled inhomogeneous network. This network structure minimizes macroscopic strain, reducing intrinsic bonding defects as well as defect precursors. This inhomogeneous CRN is enabling for applications including thermally grown ~1.5Â nm SiO2 layers for Si field effect transistor devices to optical components with centimeter dimensions. There are qualitatively similar length scales in nano-crystalline HfO2 and phase separated Hf silicates based on the primitive unit cell, rather than a ring structure. Hf oxide dielectrics have recently been used as replacement dielectrics for a new generation of Si and Si/Ge devices heralding a transition into nano-scale circuits and systems on a Si chip.
|Subjects:||Physical Science > Nanophysics|
Physical Science > Nanoelectronics
|Deposited By:||M T V|
|Deposited On:||21 Apr 2010 15:00|
|Last Modified:||21 Apr 2010 15:00|
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