Silicon infrared diffuser for wireless communication.
We show what we believe to be a novel way to use silicon in infrared radio communication as a suitable material for the realization of optical diffusers in the range of 850-1600 nm. A crystalline silicon wafer is made porous by means of electrochemical etching. The porous silicon produced is optically characterized, and measurements report a high reflectance in the band of interest. We also study the angular distribution of diffused radiation by the porous silicon surface at different angles of incident radiation. Measurements show that radiation diffuses in a quasi-Lambertian manner, confirming the good performance of this material as an incident radiation diffuser.
Influence of surface texturization on the light trapping and spectral response of silicon solar cells
A quantitative model that explains the spectral response, internal quantum efficiency, total short-circuit current, open-circuit voltage, and efficiency of high-efficiency solar cells with textured front surface and Lambertian back-surface reflectors is presented. A comparison of the textured cell characteristics is made with those of planar cells, and the separate roles of the front surface reflection coefficient and internal quantum efficiency in enhancing the short-circuit current have been investigated. It is shown that, in the case of large diffusion lengths, almost all the contribution to the increase of spectral response on texturization is due to the reduced reflection coefficient whereas, for small diffusion lengths, there is a significant increase in internal quantum efficiency on texturization, especially in the region of higher wavelengths. However, there is a small decrease in open-circuit voltage for large diffusion lengths, whereas no significant change is observed for small diffusion lengths on texturization. Nevertheless, there is a net gain in power conversion efficiency which is larger for smaller diffusion lengths. >
Third order nonlinear distortion of SAW duplexers in UMTS system
Nonlinearity distortion characterization and accurate modeling techniques for leaky surface acoustic wave (LSAW) devices have been desired in the recently years due to the applications of the Radio Frequency (RF) SAW duplexers in the third-generation (3G) telecommunication system, such as Universal Mobile Telecommunications System (UMTS). In the work, we first discuss the approaches to measure and characterize the 3rd order harmonic generation of the resonators on lithium tantalate YXl42° wafer and YXl48° wafer, with resonance frequency of 800MHz to 900 MHz; Second, we present an effective nonlinear Butterworth-van-Dyke (BVD) model to simulate the multi-tone 3rd order intermodulation effects of a band 5 duplexer; simulation result vs. measurement of 3rd order harmonic generation, 3rd order intermodulation (IMD3) and triple beat are presented.