RESUMO
This work reports the feasibility of silicon and silicon germanium epitaxy using an ASM A412(TMa) LPCVD all quartz, hot wall, vertical batch furnace reactor using 100 wafer product loads. The very same furnace can be used for 25 wafer and 200 wafer load size, without any hardware changes, dependant on production needs. Following this approach a significant cost reduction for epitaxy in 300 mm high volume manufacturing is possible and enables new applications. The native oxide of the substrate was removed by wet chemical cleaning with time coupling of less than 1 h and subsequent in-situ low pressure hydrogen anneal prior to Si or SiGe deposition. The epitaxial layers were grown using silane and germane. The Si and SiGe layers have been characterized with ToFSIMS, XRD, Raman, AFM and TEM confirming excellent crystalline quality, layer thickness and within wafer SiGe stoichiometry uniformity.
RESUMO
The electrical transport through self-assembled monolayers of alkanedithiols was studied in large-area molecular junctions and described by the Simmons model [Simmons JG (1963) J Appl Phys 34:1793-1803 and 2581-2590] for tunneling through a practical barrier, i.e., a rectangular barrier with the image potential included. The strength of the image potential depends on the value of the dielectric constant. A value of 2.1 was determined from impedance measurements. The large and well defined areas of these molecular junctions allow for a simultaneous study of the capacitance and the tunneling current under operational conditions. Electrical transport for octanedithiol through tetradecanedithiol self-assembled monolayers up to 1 V can simultaneously be described by a single effective mass and a barrier height. There is no need for additional fit constants. The barrier heights are in the order of 4-5 eV and vary systematically with the length of the molecules. Irrespective of the length of the molecules, an effective mass of 0.28 was determined, which is in excellent agreement with theoretical predictions.
