• Home
• Agenda
• Registration
• Call For Presentations
• Information For Presenters
• Sponsors
• Travel Information
• Lodging
• On-Campus Parking & Transportation
• Optional Social Events
• Contact Information

Agenda

Session 1: Silicon Nanostructures

• 08:30–08:50
  Hybrid Semiconductor/Nanoelectronic Circuit Architectures
  Konstantin K. Likharev
  Stony Brook University, Stony Brook, NY 11794-3800
  
  I will present a review of the recent work on hybrid semiconductor/nanodevice integrated circuits. Such a circuit combines a CMOS subsystem, fabricated with the usual lithographic patterning, and a nanowire crossbar with simple bistable two-terminal devices at each crosspoint, fabricated by advanced (e.g., nanoimprint) patterning. The CMOS and nano subsystems are connected with an area-distributed “CMOL” interface which allows the CMOS subsystem to address every nanodevice, even without nanoscale alignment of the two subsystems. Detailed simulations have shown that the hybrid circuits may serve as the basis for: (i) terabit-scale memories with access time below 100 ns and defect tolerance up to 10%, (ii) FPGA-like reconfigurable logic circuits with density about two orders of magnitude higher than that of CMOS FPGAs (fabricated with similar design rules), and (iii) mixed-signal neuromorphic networks (“CrossNets”) which may become the first hardware basis for challenging the human cerebral cortex in both areal density and speed. Recently the work on the hybrid CMOS/nano circuits received a strong boost from the experimental demonstration of highly reproducible metal-oxide devices with the necessary functionality and nanowire crossbars with sub-30-nm half-pitch. As a result, it seems that all CMOL components are ready for the first integration attempts.
• 08:50–09:10
  Nanocrystallite Si Based MOS Light Emitting Diodes
  Gong-Ru Lin
  Graduate Institute of Electro-Optical Engineering, National Taiwan University, Taiwan R.O.C.
  
  The optical properties of a SiOx film rapid-thermal-annealed (RTA) by CO2 laser are primarily investigated. The micro-photoluminescence (µ-PL) and HRTEM analysis indicate that the precipitation of random-oriented Si nanocrystals can be initiated when laser intensity (Plaser) larger than 4.5 kW/cm2. At Plaser of 6 kW/cm2, the Si nanocrystals exhibits a largest diameter of 8 nm and a highest density of 4.5×1016 cm-3, which emits strong PL at 790-825 nm. The micro-photoreflectance of the CO2 laser RTA SiOx film reveals a volume-density-product dependent refractive index increasing from 1.57 to 1.87 as the Plaser increases from 1.5 to 7.5 kW/cm2. Nonetheless, the laser ablation of SiOx film occurs with a linear ablation slope of 35 nm/kW/cm2 at beyond 7.5 kW/cm2, which terminates the enlargement of Si nanocrystals, degrades the near-infrared PL, and slightly reduces the refractive index of the CO2 laser RTA SiOx film. With such a CO2 laser annealed SiOx film, we are able to fabricate a metal-oxide-semiconductor light-emitting diode with turn-on voltage and current of 79 V and 33 mA/cm2, respectively. The CO2 RTA SiOx based MOSLED emits output power up to 29 nW with a P-I slope of P-I slope: 4.4 mW/A. We further show a preliminary data of a MOSLED grown on Si surbstrate with interfacial Si nano-pyramid, which further enhances the quantum efficiency to >10-4 and electroluminescent power of >0.1 µW.
• 09:10–09:30
  Trigate Silicon Nanowire Transistors: The Role of Interactions
  M.J. Gilbert, D. Basu, and S.K. Banerjee
  Microelectronics Engineering Research Center, University of Texas at Austin
  
  As the march towards ever smaller silicon devices continues unabated, we are rapidly approaching size scales where the bulk silicon transistor can no longer deliver sufficient device performance. Of the many different devices under consideration to replace the bulk silicon transistor, one of the most interesting is the nanowire transistor. Because of the size of these devices, there have been many approaches to implement full quantum mechanical simulations. To date, most of these approaches have considered only ballistic transport. In this talk, we will use the recursive scattering matrix method to calculate the three dimensional transport properties of silicon nanowire transistors in the presence of a variety of interactions including electron-impurity, electron-phonon and surface roughness scattering. We find that while it is possible to recover much of the ballistic behavior of silicon nanowire transistors in the presence of elastic scattering, the inclusion of the electron-phonon interaction significantly alters the transport characteristics.
• 09:30–09:45
  Si/Ge light emitters
  Chee Wee Liu
  Department of Electrical Engineering, National Taiwan University, Taiwan
  
  The Si-based photonics can not only potentially expand the functionalities of Si chips such as optical interconnect, photodetection, and light emission, but also probe the electron-photon interaction in the indirect bandgap material systems with different momentum conservation processes. The metal-insulator- semiconductor (MIS) tunneling structure is used to introduce the electron-hole radiative recombination with the involvement of the roughness scattering, phonon scattering, and localization of carriers to reach the momentum conservation. The MOS light emitter has the advantage of simple process without the pn junction formation. The minority carriers tunnel from the gate electrode and recombine with the majority carriers at the insulator/semiconductor interface at accumulation bias. By the incorporation of SiGe quantum dots and quantum wells, the emission wavelength can be tuned from 1.1, 1.3, and 1.5 to 2.2 µm due to the bandgap shrinkage by the strain and Ge incorporation. The ~ 2 µm emission can be obtained by the type II heterojunction recombination between the Si conduction band and SiGe valence band. The external strain is used to further change the emission wavelength. The electron-hole-plasma recombination model can fit the emission spectra and extract the bandgap information. The strain-induced wavelength shift can be quantitatively understood by deformation potential theories. Similarly, a MOS type detector can be made and operated at the inversion bias. Finally, the digital communication between the MOS LEDs and MOS detectors using 1.8 µm wavelength is demonstrated.
• 09:45–10:00
  Hydrophobic Fluorinated Polyhedral Oligomeric SilSesquioxanes
  Joseph M. Mabry
  Air Force Research Laboratory, Propulsion Directorate, Edwards AFB, CA 93524
  
  Polyhedral oligomeric silsesquioxanes (POSS) are organic/inorganic hybrid materials that contain both silicon-oxide and organic functionality. In current work, POSS building blocks seem to be non-interacting. Specifically, the organic groups surrounding the silsesquioxane core are composed of fluoroalkyl moieties. Fluoroalkyl compounds are known to be rather inert. This is largely because they are non-polarizable and have low surface free energies.

  Various surface properties of the FluoroPOSS compounds have been examined. The Fluoro­decyl POSS has a water contact angle of 154°, which is approximately 40° higher than the water contact angle of PTFE. However, not all FluoroPOSS compounds are so hydrophobic. Examination of crystal structures gives and indication of the reason for the difference. The molecular-scale surface roughness of the Fluorodecyl POSS is much greater that the other FluoroPOSS compounds. This nano-scale roughness, in combination with the micro-scale processing roughness, leads to the improved hydrophobicity. This may be similar to the surface found on the leaves of a Lotus plant, where nano-scale and micro-scale roughness combine to provide ultrahydrophobicity.

  These materials are monodisperse and crystalline. This paper will discuss many of the parameters and properties of FluoroPOSS materials. AFM images will be used to illustrate surface roughness. Water contact angles and critical surface tension calculations will be used to describe surface properties.

  Cleared as AFRL-ERS-PAS-07-017.