TY - JOUR A1 - Schmidt, Oliver G. A1 - Denker, Ullrich A1 - Dashiell, Michael W. A1 - Jin-Phillipp, Neng Yun A1 - Eberl, Karl A1 - Schreiner, Rupert A1 - Gräbeldinger, Hedwig A1 - Schweizer, Heinz C. A1 - Christiansen, Silke H. A1 - Ernst, Frank T1 - Laterally aligned Ge/Si islands: a new concept for faster field-effect transistors JF - Materials Science and Engineering B N2 - Self-assembled and coherently strained Ge dots were grown on a Si/SiGe superlattice, which was deposited on a flat Si(001) substrate surface patterned with a regular array of straight trenches. The superlattice translates the surface modulation of the substrate into a strain-field modulation, which causes the Ge dots on its surface to form along straight lines above the buried trenches. This approach provides self-assembled Ge dots with excellent lateral periodicity, which might be useful for fabricating dot-based field-effect-transistors (DotFETs). Here, we propose the concept of a modulation-doped p-channel DotFET (p-MOD-DotFET). The p-MOD-DotFET relies on embedded Ge-rich nanostructures, which provide p-channels through the Ge-rich dots. A high Ge concentration in the dots is desirable in order to exploit the high hole mobility of Ge-rich material. We show that the commonly observed Si–Ge intermixing during Si capping of Ge dots can be suppressed by overgrowing the islands at low temperature. KW - Field-effect transistor KW - Self-assembly islands KW - CMOS KW - MOSFET KW - MOFDET alignment KW - Modulation Y1 - 2002 U6 - https://doi.org/10.1016/S0921-5107(01)00810-8 SN - 1873-4944 SN - 0921-5107 VL - 89 IS - 1-3 SP - 101 EP - 105 PB - Elsevier CY - New York, NY ER - TY - CHAP A1 - Schiek, Roland A1 - Baronio, Fabio T1 - Spatial Akhmediev Breathers in Slab Waveguides T2 - 2019 Conference on Lasers and Electro-Optics Europe European Quantum Electronics Conference (CLEO/Europe-EQEC), 23-27 June 2019, Munich, Germany N2 - Summary form only given. The analytical breather-solutions of the Nonlinear Schrödinger Equation (NLS) [1] have been intensively studied and verified experimentally in the time-space system of optical pulse propagation in fibers [2]. In space-space systems, i.e. in optical beam propagation breathers in ultra-fast nonlinear media have not been observed due to the breather’s infinite background and a resulting extremely large power. In a lithium niobate slab waveguide with two second-harmonic (SH) resonances the resulting quasi-cubic cascaded quadratic nonlinearity provided together with the intrinsic cubic susceptibility enough nonlinearity for breather excitation at experimentally reachable powers. We could characterize the fi rst ultra -fast spatial -spatial optical breathers in a 5 -cm -long titanium indiffused lithium niobate slab waveguide at power levels down to tens of kW. The guided fundamental wave (FW) TM° fi lm mode at A = 1.32μm is phase -matched for type -I SH generation to TE 0 and TEi SH modes at temperatures near 295 and 344C. With temperature tuning the phase -mismatch and the two effective cascaded nonlinearities were adjusted. For breather observation, we aimed for a large phase -mismatch with low SH levels such that the cascaded nonlinearity is quasi -cubic and the propagation is well approximated by the NLS and its breather solutions. A frequency -doubled Nd:YAG-pumped OPA with CW-seeding delivered 5-ps long pulses with up to 200kW peak power in the waveguide. With a cylindrical telescope the beam was transformed into a very wide elliptical beam to approximate the breather background. The beam was end -fire coupled into the FW TM () mode. A variable few % of the beam were separated and coupled with a tilt and good overlap to the main beam into the waveguide to produce a spatial modulation of the input with adjustable period and modulation depth. A beam width of 1.5mm was large enough in the compromise between available beam power and infinite beam width. A beam with a transverse modulation with periods between 130 to 300μm approximates a constant background with modulation well enough to trigger modulation instability that develops eventually into the breather. KW - Frequency conversion KW - lithium niobate KW - Modulation KW - Optical beams KW - Optical pulses KW - Optical waveguides KW - Slabs Y1 - 2019 U6 - https://doi.org/10.1109/CLEOE-EQEC.2019.8872896 ER -