The optimizations of the emitter region and the metal grid of a concentrator silicon solar cell are illustrated. The optimizations are done under 1 sun,100 suns and 200 suns using the 2D numerical simulation tool TCAD software.The optimum finger spacing and its range decrease with the increase in sheet resistance and concentration ratio.The processes of the diffusion and oxidization in the manufacture flow of the silicon solar cells were simulated to get a series of typical emitter dopant profiles to optimize.The efficiency of the solar cell under 100 suns and 200 suns increased with the decrease in diffusion temperature and the increase in oxidation temperature and time when the diffusion temperature is lower than or equal to 865℃.The effect of sheet resistance of the emitter on series resistance and the conversion efficiency of the solar cell under concentration was discussed.
A 16 channel arrayed waveguide grating demultiplexer with 200 GHz channel spacing based on Si nanowire waveguides is designed.The transmission spectra response simulated by transmission function method shows that the device has channel spacing of 1.6 nm and crosstalk of 31 dB.The device is fabricated by 193 nm deep UV lithography in silicon-on-substrate.The demultiplexing characteristics are observed with crosstalk of 5-8 dB,central channel’s insertion loss of 2.2 dB,free spectral range of 24.7 nm and average channel spacing of 1.475 nm.The cause of the spectral distortion is analyzed specifically.
A new technique to generate a millimeter（mm）-wave carrier of 32.57 GHz(fLO=10.85 GHz) with single sideband modulation（SSB） for radio-over-fiber（RoF） systems is experimentally demonstrated by using stimulated Brillouin scattering（SBS）.The SSB is realized by directly amplifying the +3rd sideband of the modulated optical carrier in the process of SBS.The pump wave is provided through a double Brillouin scattering frequency shifting configuration.The use of the same laser source to generate the pump wave ensures the stability of the mm-wave generation system since the relative frequency shift between them can be eliminated.In addition, the mm-wave carrier obtains an RF power gain of 21 dB with the SBS amplification and a 3-dB bandwidth of 10kHz.
Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal–oxide–semiconductor transistors and efficient photonic devices.In this paper,we design the Ge nano-belts on an insulator surrounded by Si3N4or SiO2for improving their tensile strain and simulate the strain profiles by using the finite difference time domain(FDTD) method.The width and thickness parameters of Ge nano-belts on an insulator,which have great effects on the strain profile,are optimized.A large uniaxial tensile strain of 1.16% in 50-nm width and 12-nm thickness Ge nano-belts with the sidewalls protected by Si3N4is achieved after thermal treatments,which would significantly tailor the band gap structures of Ge-nanobelts to realize the high performance devices.
An ultra compact triplexing filter was designed based on a silicon on insulator(SOI) nanowire arrayed waveguide grating(AWG) for fiber-to-the-home FTTH.The simulation results revealed that the design performed well in the sense of having a good triplexing function.The designed SOI nanowire AWGs were fabricated using ultraviolet lithography and induced coupler plasma etching.The experimental results showed that the crosstalk was less than -15 dB,and the 3 dB-bandwidth was 11.04 nm.The peak wavelength output from ports a,c,and b were 1455,1510 and 1300 nm,respectively,which deviated from our original expectations.The deviation of the wavelength is mainly caused by 45 nm width deviation of the arrayed waveguides during the course of the fabrication process and partly caused by material dispersion.
A 10-channel,200 GHz channel spacing InP arrayed waveguide grating was designed,and the deep ridge waveguide design makes it polarization independent.Under the technologies of molecular beam epitaxy, lithography,and induced coupler plasma etching,the chip was fabricated in our laboratory.The test results show that the insertion loss is about -8 dB,and the crosstalk is less than -17 dB.
