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Herein, a DC and microwave performance of 2 μm gate length AlGaN/GaN high‐electron‐mobility transistor (HEMTs) on a Mn‐doped GaN substrate is demonstrated. The maximum drain current is 670 mA with a threshold voltage of −$-$2.5 V and with good pinch‐off characteristics. The breakdown voltage of the HEMT is ≈80 V. The HEMT shows Δ8% current collapse while referenced HEMT on a SiC substrates which is fabricated simultaneously shows large Δ30% current collapse. When the HEMT with a gate width of 100 μm is tuned for the maximum output power at 2.4 GHz with a drain voltage of 30 V, it delivers 500 mW (5 W mm−1) with the maximum drain efficiency of 54%. These output performances are in good agreement with ideal class‐A operation performance. Therefore, it is concluded that the HEMT on Mn‐doped GaN substrates is promising for future microwave and millimeter‐wave high‐power transistors. [ABSTRACT FROM AUTHOR]

A novel electron emitter utilizing the characteristics of ferroelectric ceramic materials has been developed. The electron-emitting portion of the electron emitter has a unique micro-structure which has the vacuum gap between an upper electrode and the surface of a ferroelectric layer. We confirmed electron emission by a three-step process which consists of electron charge (the first step), charge retention (the second step), and electron emission (the third step). The ferroelectric hysteresis in the process indicates unique characteristics as follows. At the first step, remnant polarization of the same level as the completely adhered electrode structure is obtained in spite of a vacuum gap because the electron charge develops from the upper electrode to the surface of the ferroelectric layer under the vacuum gap in synchronism with the polarization reversal of the ferroelectric layer. On the other hand, at the third step, the electric field in the vacuum gap advances electron emission while the development of the polarization reversal inhibits the return of the electron charge along the surface of the ferroelectric layer. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(6): 21-30, 2009; Published online in Wiley InterScience (). DOI 10.1002/ecj.10083 [ABSTRACT FROM AUTHOR]

Rad51, Rad52, and RPA play central roles in homologous DNA recombination. Rad51 mediates DNA strand exchange, a key reaction in DNA recombination. Rad52 has two distinct activities: to recruit Rad51 onto single-strand (ss)DNA that is complexed with the ssDNA-binding protein, RPA, and to anneal complementary ssDNA complexed with RPA. Here, we report that Rad52 promotes annealing of the ssDNA strand that is displaced by DNA strand exchange by Rad51 and RPA, to a second ssDNA strand. An RPA that is recombination-deficient (RPA(rfa1-t11)) failed to support annealing, explaining its in vivo phenotype. Escherichia coli RecO and SSB proteins, which are functional homologues of Rad52 and RPA, also facilitated the same reaction, demonstrating its conserved nature. We also demonstrate that the two activities of Rad52, recruiting Rad51 and annealing DNA, are coordinated in DNA strand exchange and second ssDNA capture. [ABSTRACT FROM AUTHOR]