Structure and Semiconducting Character of a Polymeric Iodoplumbate Coordination Complex

A new polymeric iodoplumbate complex [Zn(DMF)6][Pb2I6] 1 has been prepared and characterized by elemental analysis and single-crystal X-ray analysis. Its structure contains infinite iodoplumbate chains constructed by the [PbI5] subunit. EHT crystal orbital calculation and the experimental results show that this material is an unconventional semiconductor and the electrical character is associated with its structural feature.     

High-Current Multi-Finger Mesa InGaAs/InP DHBTs

Characteristics of single- and multi-finger mesa InGaAs/InP double heterojunction bipolar transistors （DHBTs） are compared. The current gain decreases with the increasing number nf of the emitter fingers due to the mutual thermal interaction between the fingers. The Kirk current can be as high as 150mA for four-finger DHBT. No degradation of the peak of the current gain cutoff frequency ft is found for multi-finger DHBTs. The peak of the maximum oscillation frequency fmax decreases with an increase of nf due to the increasing parasitic resistance of the base. The results are very helpful for applications of the common-base DHBTs in power amplifiers operating at very high frequencies.     

Triply Linked Corrole Dimers

The oxidation of 10–10′ singly linked corrole dimers with DDQ at low concentration in CHCl₃ afforded meso–meso, β–β, β–β triply linked 2H‐corrole dimers (with two inner NH groups in each corrole unit), which exhibited characteristic ¹H NMR and absorption spectra attributable to their nonaromatic electronic networks. These 2H‐corrole dimers were reduced with NaBH₄ to aromatic 3H‐corrole dimers, which were unstable and easily oxidized back to the 2H‐corrole dimers upon exposure to air. Bis(zinc(II)) complexes of the 2H‐corrole dimers were synthesized and characterized as rare examples of nonaromatic zinc(II) corrole complexes.     

Effects of controllable process factors on Al rear surface bumps in Si solar cells

High efficiency solar cells require good back surface field passivation and high back reflectance in the rear Al region. In module processes, wafer-based solar cell can break through stress during soldering uneven rear aluminum surfaces - a serious problem that affects throughput. This work examined rear surfaces with respect to controllable process factors such as ramping and cooling rates during rapid thermal processing, and the fineness of aluminum powder used in the screen-printed paste. A faster ramp up rate resulted in a uniform temperature gradient between the aluminum and silicon surfaces. As a results, the bumps on the aluminum surface were small and of high density. Fine aluminum metal powder in the paste for screen-printing contact points resulted in large distribution, high density bumps. Bumps formed during cooling in metallization, their sizes and densities were dependent the on uniformity of the aluminum and silicon liquid wetting of the silicon surface.